Symposium Organizers
Ram Seshadri University of California-Santa Barbara
Joseph W. Kolis Clemson University
David B. Mitzi IBM T. J. Watson Research Center
Matthew J. Rosseinsky The University of Liverpool
QQ1: Polar and Optical Materials
Session Chairs
Tuesday PM, November 28, 2006
Grand Ballroom (Sheraton)
9:00 AM - **QQ1.1
Structure Control in Perovskites: Bi Ferroelectrics and Li Checkerboards.
Peter Davies 1 , Beth Guiton 1 , David Stein 1 , Matthew Suchomel 1 , Josh Furman 1
1 Materials Science and Engineering, University of Pennsylvania, Philadelphia, Pennsylvania, United States
Show AbstractThe flexibility of the perovskite structure in accommodating a broad spectrum of chemical substitutions has led to the discovery of many materials with unique functional and multi-functional responses. The first part of this talk will focus on Bi-based perovskites which are the focus of considerable attention for applications as lead-free ferroelectrics and piezoelectrics. In solid solution with lead titanate almost all known additives reduce the tetragonal distortion of the perovskite structure and induce the formation of a morphotropic phase boundary. However, recently we found that certain combinations of A and B-site substituents, in particular Bi and Zn, induce large and sustained increases in the tetragonality of lead titanate and increase the Curie temperature by several hundreds of degrees. The properties of these systems are critically dependent upon the coupling of the ionic displacements on the A and B-site sub-lattice and the highest Tc’s are observed in solid solutions of Bi(Zn1/2Ti1/2)O3 and Bi(Zn3/4W1/4)O3. The unusual responses are not limited to these systems and by tailoring the chemistry with combinations of Bi, Cu, Mg, Zn, and Nb new families of relaxor ferroelectric materials can also be prepared. The second part of the talk will focus on a family of A-site deficient perovskites where the ionic displacements induce multiple degrees of ordering on different length scales. When the chemistry of the A-site includes a mixture of rare earth cations, vacancies, and “under-sized” cations such as Li, a complex combination of ion displacements and ordering produce a modulated, phase separated, nano “checkerboard” structure with periodicities on the order of 10nm. The levels of perfection of these unusual phase separated structures are unprecedented in an oxide perovskite. The crystal-chemical driving forces, methodologies for controlling the periodicity and the potential applications of the checkerboard structures will be discussed.
9:30 AM - QQ1.2
New Phases in the Bi2O3-Fe2O3-Nb2O5 System Exhibiting “Chemically Twinned” Pyrochlore Intergrowth Structures
Ian Grey 2 , W. Mumme 2 , Terrell Vanderah 1 , R. Roth 1 , Igor Levin 1
2 , CSIRO Minerals, Clayton South, Victoria, Australia, 1 Ceramics Division, NIST, Gaithersburg, Maryland, United States
Show AbstractA subsolidus phase equilibria study of the Bi2O3-Fe2O3-Nb2O5 system indicated the formation of four ternary phases: pyrochlore, Aurivillius-type Bi3Fe0.5Nb1.5O9, and two phases with approximate stoichiometries Bi17Fe2Nb31O106 and Bi17Fe3Nb30O105 that appeared to be structurally related to the binary compound known as Bi8Nb18O57. Structural determinations of the latter three related phases were carried out using single-crystal X-ray diffraction and neutron powder diffraction. We describe here the crystal chemistry of these phases in comparison to the pyrochlore and hexagonal tungsten bronze structures.
9:45 AM - QQ1.3
Design of New Structural Types from Oxocentered Tetrahedra : Continuous Polycationic Series from 1D Chains to 2D Planes in New Bismuth Compounds.
Olivier Mentré 1 , Colmont Marie 1 , Marielle Huve 1
1 chemistry Dpt, UCCS, equipe de Chimie du Solide, Villeneuve d'Ascq cédex France
Show Abstract10:00 AM - QQ1.4
Phase Formation and Dielectric Properties of Ln3NbO7 (Ln = Rare Earth Elements).
Lu Cai 1 , Juan Nino 1
1 materials science and engineering, university of florida, Gainesville, Florida, United States
Show AbstractCurrent and future generation of electronic devices require stable dielectric materials that show among others intermediate dielectric constant, low dielectric loss, and low temperature coefficient of capacitance. In this work, the fundamental relationships between crystal structure and dielectric properties of Ln3NbO7 ceramics (where Ln = rare earth elements) are investigated. The variation in the crystal structure of Ln3NbO7 from orthorhombic weberite-type structures to a cubic defect fluorite structure as a function of composition, as well as an approximately linear relationship between the polarizability and the ionic radius of Ln3+, provide an ideal stage for studying the correlation between polarizability and dielectric properties in fluorite-related structures. It is experimentally observed that, with the exception of Gd3NbO7, at 1 MHz the room temperature dielectric permittivity of Ln3NbO7 (Ln = Nd, Dy, Er, Yb and Y) decreases from approximately 41 to 30 with increasing ionic radius of Ln3+. At 1 MHz and room temperature, the observed dielectric loss is in on the order of 10^(-4) for the weberite-type structures and 10^(-3) for the defect fluorite structure. The permittivity of Ln3NbO7 (Ln= Nd, Dy, Er, Yb and Y) increases with the increasing temperature between 110 K and 470 K. The loss is relatively stable up to 350 K, where it increases with a rise in temperature. Of particular interest is Gd3NbO7 that crystallizes with a weberite-type structure (space group C2221) and exhibits dielectric relaxation behavior. A detail analysis of the crystal structure-dielectric property relationships observed in Ln3NbO7 ceramics will be presented, and a possible explanation for the origin of the dielectric relaxation in Gd3NbO7 will be discussed.
10:15 AM - QQ1.5
Novel Ferroelectric Bi-based Perovskites: Tetragonal Bi2(ZnTi)O6 and its Derivatives.
Matthew Suchomel 1 , Mathieu Allix 1 , Andrew Fogg 1 , Matthew Rosseinsky 1
1 Department of Chemistry, University of Liverpool, Liverpool United Kingdom
Show AbstractWhile Pb-containing perovskite oxides currently dominate ferroelectric and piezoelectric devices, increasing regulatory restrictions on their use have recently inspired considerable research into the search for Pb-free materials displaying comparable figures of merit. Environmentally benign Bi based oxides are one promising alternative, given the similar electronic configurations of Bi+3 and Pb+2, and have therefore been explored recently in a variety of experimental and theoretical studies. However, compared to the Pb-based perovskite family, still relatively few ferroelectric Bi-based compounds have been reported. In the current study we report the synthesis of new, ambient pressure stable, Bi perovskite oxides by high pressure methods. Powder neutron diffraction, variable temperature synchrotron XRD, Raman spectroscopy, TEM techniques, and dielectric permittivity measurements have been used to characterize the structure and properties of these new compounds. In particular, the highly tetragonal perovskite Bi2(ZnTi)O6, new Pb-free ferroelectric compound with an extremely high TC and calculated ionic polarization of over 150 μC cm-2, is discussed. Its c/a ratio of 1.21 is the highest reported to date for any d0 B site Pb or Bi based perovskite. Bi2(ZnTi)O6, in essence a new Bi-based analogue to PbTiO3, and its derivatives may prove a significant development on the path to Pb-free ferroelectric materials; further work aimed at exploiting the unique properties of Bi2(ZnTi)O6 will be discussed.
10:30 AM - QQ1:PolOpt
BREAK
11:00 AM - **QQ1.6
Solution-processed Oxide Films, Nanolaminates, Devices, and Integrated Circuits.
Douglas Keszler 1 , Jeremy Anderson 1 , Stephen Meyers 1 , Hai Chiang 2 , Tran Phung 3 , Gregory Herman 4 , David Johnson 3 , John Wager 2
1 Chemistry, Oregon State University, Corvallis, Oregon, United States, 2 Electrical Engineering and Computer Science, Oregon State University, Corvallis, Oregon, United States, 3 Chemistry, University of Oregon, Eugene, Oregon, United States, 4 Advanced Materials and Processes Lab, Hewlett Packard Company, Corvallis, Oregon, United States
Show Abstract11:45 AM - QQ1.8
Phase Stability and Dielectric Properties of HfO2-based Solid Solutions.
Eric Cockayne 1 , Benjamin Burton 1
1 Ceramics Division, NIST, Gaithersburg, Maryland, United States
Show AbstractHfO2 has emerged as a leading candidate for analternate high-k gate dielectric material. Given that optimal materials properties are often realized in solid solutions, we investigate the properties of hafnia-based solid solutions. We use first-principles calculations to explore the effects of ionic substitution on the stability, lattice dynamics, anddielectric properties of hafnia. In particular, the effects of partial Ti substitution on the Hf site, as well as partial Ta substitution on the Hf site compensated by partial N substitution on the O site are studied.
12:00 PM - QQ1.9
Origin of The Gigantic Dielectric Response in CaCu3Ti4O12 Oxide
Jincheng Zheng 1 , Lijun Wu 1 , Yimei Zhu 1
1 , Brookhaven National Lab, Upton, New York, United States
Show AbstractThe huge dielectric-constant (~10^5) of non-ferroelectric CaCu3Ti4O12 (CCTO) oxide over a wide range of temperature and frequency recently attracted much scientific attention. This intriguing property affords promising technological applications, such as miniaturization of static- and dynamic-random access memories, and hence, warrants a full investigation. After an exhausting search for the intrinsic origin (a stoichiometric defect-free single-domain crystal) of this unusual behavior by neutron-, x-ray-, and electron-experiments, as well as Density Functional Theory (DFT) calculations, attention shifted to structural defects related to the extrinsic nature of the material that forms the “Internal Barrier Layer Capacitance” (IBLC) responsible for this atypical permittivity. The puzzling aspect of the observations was that the long-expected twin boundaries in the system act as IBLC were never been observed. Furthermore, in the single crystal, sintered ceramic and thin film form of CCTO, the type and density of the defects are very different, yet all show similar dielectric behavior, the origin of which has become a long-standing mystery. Here we show our integrated studies of CCTO, using quantitative electron diffraction, synchrotron x-ray diffraction, extended x-ray absorption fine structure spectroscopy, and DFT calculations to understand its local lattice and electronic structure. Our results offer new insights into the origin of the dielectric behavior and undoubtedly indicate there exists significant disorder involving Cu replacing Ca, and vice versa in the system. Theoretical analysis of the local symmetry reveals that such disorder can lead to a local metallic-like dielectric response. This local enhancement of dielectric response and its strong proximity effect provide a novel microscopic ground of the puzzling high dielectric constant of this materials, and suggest a new route to synthesizing high-dielectric materials based on disordered degenerate Mott-insulators.The authors acknowledge the collaborations with A. Frenkel, J. Hanson, W. Ku, M. Cohen, and S. Wakimoto. This work was supported by the U.S. DOE, under Contract No. DE-AC02-98CH10886.
12:15 PM - QQ1.10
Studies of Complex Perovskites: Structure, Bonding and Properties
Patrick Woodward 1
1 Department of Chemistry, Ohio State University, Columbus, Ohio, United States
Show AbstractPerovskites are among the most flexible structure types in terms of chemical substitution, structural distortions and the ability to tolerate large concentrations of vacancies. In this talk I will explore the synergistic interaction between cation and anion ordering and structural distortions. In particular attention will be paid to class of perovskites with stoichiometry, AA'MM'O6, which possess both layered ordering of A-site cations and rock salt ordering of B-site cations. The electrical (including dielectric) and magnetic properties of a number of new perovskites will be presented.
QQ2/AA5: Joint Session: Solid State Chemistry of Ionic Conductors
Session Chairs
Allan Jacobson
Silvia Licoccia
Tuesday PM, November 28, 2006
Grand Ballroom (Sheraton)
2:30 PM - **QQ2.1/AA5.1
Mesoporous Transition Metal Oxides for Energy Storage.
Feng Jiao 1 , Shaju Kuthanapillil 1 , Peter Bruce 1
1 Chemisty, University of St Andrews, St Andrews United Kingdom
Show AbstractMesoporous materials based on main group elements are well established; this is not the case for transition metal oxides, in part because their synthesis has proved more intractable. Yet mesoporous transition metal oxides can exhibit many unique and important properties leading to a diverse range of applications. The synthesis and characterisation of several ordered mesoporous transition metal oxides with highly crystalline walls, α-Fe2O3, γ-Fe2O3, Fe3O4 (inverse spinel), Mn3O4 (spinel), low temperature-LiCoO2, will be described as will the significance of such materials in enabling a step change in the performance of energy storage devices, vital to address the problem of global warming.The synthesis of mesoporous transition metal compounds is often limited to transition metals in oxidation states that are stable in solution. We have synthesised several of the above ordered mesoporous materials, e.g. Fe3O4 and Mn3O4, by reducing/oxidising other ordered mesoporous transition metal oxides, e.g. Fe2O3 and Mn2O3, while preserving the ordered mesostructures throughout, thus enabling access to new mesoporous transition metal compounds. LT - LiCoO2 was synthesised by reacting mesoporous Co3O4 with LiOH in the solid-state, converting the former to the low temperature polymorph of LiCoO2, with preservation of the ordered mesostructure and with a high level of crystallinity in the walls.The magnetic properties of crystalline mesoporous materials are distinct from those of the corresponding bulk phases and from nanoparticulate forms of the same material in which the nanoparticle diameter is comparable to the thickness of the walls. Data on the magnetic behaviour will be presented.LT-LiCoO2 is an intercalation host from which lithium may be removed and re-inserted. As a mesoporous material, when used as an electrode in key energy storage devices such as rechargeable lithium batteries, the electrolyte can flood the pores providing a high surface area in intimate contact with the electrode. Furthermore, the thin walls (typically 7 nm) provides short diffusion distances for Li+ and e– on intercalation/deintercalation. Both features lead to rapid intercalation processes and much greater reversibility than is the case for corresponding nanoparticulate LT-LiCoO2. The ordered mesostructure is preserved on repeated intercalation/deintercalation. Data on the superior properties of the mesoporous material as an energy storage electrode will be presented.
3:00 PM - QQ2.2/AA5.2
Nonstoichiometry of Vanadium (IV) Oxide.
Dilan Seneviratne 1 , Harry Tuller 1
1 Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States
Show Abstract3:15 PM - QQ2.3/AA5.3
New Insights Into The Formation Of Organically Templated Vanadium Oxides.
Arunachalam Ramanan 1 2 , M Stanley Whittingham 2
1 Chemistry, Indian Institute of Technology, Delhi, New Delhi , Delhi, India, 2 Chemistry and Materials Research Center, Binghamton University, Binghamton, New York, United States
Show Abstract3:30 PM - QQ2.4/AA5.4
Bio-controlled Synthesis of Nanostructured Vanadium Oxides.
Olivier Durupthy 1 , Axel Marchal 1 , Nathalie Steunou 1 , Thibaud Coradin 1 , Gervaise Mosser 1 , Jacques Livage 1
1 Université Paris 6, Chimie de la Matière Condensée de Paris, Paris France
Show Abstract3:45 PM - QQ2.5/AA5.5
Exploring Ionic Conductivity Mechanisms in Interfaces and Nanoparticles Using Magic-angle Spinning Nuclear Magnetic Resonance (MAS NMR).
Stephen Boyd 1 , Clare Grey 1
1 Chemistry, Stony Brook University, Stony Brook, New York, United States
Show AbstractSeveral systems, including solid oxide fuel cells (SOFC) and gas sensors, rely on fast, reliable ionic conductivity within particles and at interfaces. Consequently, much research has centered on finding new materials that can support fast ionic movement at a reasonable temperature and at understanding conduction mechanisms. Here, two systems were studied in an attempt to investigate interfacial and surface phenomena. First, a heterostructurual material consisting of thin, alternating layers of BaF2 and CaF2 deposited by molecular beam epitaxy (MBE) was investigated by using 19F MAS NMR. New resonances were observed, in addition to those due to BaF2 and CaF2, and the relaxation times of all these peaks were investigated as a function of temperature. Second, nanoparticles of BaF2, treated with the a super-Lewis acid, SbF5, were studied by NMR as a function of loading level. SbF5 treatment resulted in the creation of local environments with very short spin-lattice relaxation (T1) times, indicating enhanced ionic mobility. More detailed NMR experiments are currently in progress to correlate ionic mobility with local structure.We thank Prof. J. Maier for providing the heterostructure sample and for helpful discussions.
4:30 PM - **QQ2.6/AA5.6
Ionic and Mixed Conductors for Energy: Preparation and Properties.
Philippe Knauth 1
1 MADIREL, University of Provence, Marseille France
Show Abstract5:00 PM - QQ2.7/AA5.7
Electrochemical Synthesis of Inorganic Films Containing Ordered Nanoporous Structures Using Interfacial Surfactant Templating.
Ellen Steinmiller 1 , Ryan Spray 1 , Matthew Yarger 1 , Nikhlendra Singh 1 , Kyoung-Shin Choi 1
1 Department of Chemistry, Purdue University, West Lafayette, Indiana, United States
Show Abstract Porous electrodes have been the center of interest in the development of devices for use in energy production, catalysis, and sensing application. By providing an enhanced surface area per unit volume, porous structures can significantly improve the kinetics and mass transfer at the interfaces of electrodes, thus enhancing the efficiency of various chemical and electrochemical reactions. Creating electrodes with ordered nanoporous structures is of special interest because it not only increases surface areas enormously but also makes it possible to study the effect of specific nanostructural details (i.e. pore sizes and pore connections) on chemical and physical properties of the electrodes. In this presentation, we introduce an electrochemical strategy for producing inorganic nanoporous films by utilizing self-assembly of amphiphilic molecules at solid-liquid interfaces for electrodeposition. The spontaneous aggregation of amphiphiles at solid-liquid interfaces is a well-established phenomenon. Surface micelles form at concentrations well below the critical micelle concentration (cmc) because the surface forces increase the interfacial concentration of amphiphiles. The novelty of our approach lies in exploiting these phenomena for inorganic synthesis by combining it with electrodeposition. This can be achieved by using a working electrode for both the organic assemblies and inorganic deposition. By selecting surfactants with appropriate hydrophilic groups, the metal ions that need to be deposited can be strongly bound on the surface of surfactant micelles as counter ions, thereby forming stable organic-inorganic interfacial aggregates. When an electrical bias is applied to initiate the deposition process, the organization of these metal ions in the interfacial assemblies directly becomes the skeleton of the inorganic deposits, resulting in ordered inorganic nanostructures. In this presentation, we will explain the principles of our electrochemical interfacial surfactant templating method in detail and discuss synthesis and characterization of several oxide and hydroxide films (e.g. zinc oxide, tin oxide) containing various nanoporous structures.
5:15 PM - QQ2.8/AA5.8
Anisotropy in Layered Polymer-Clay Nanocomposite Electrolytes.
Jodie Lutkenhaus 1 , Paula Hammond 1
1 Chemical Engineering, MIT, Cambridge, Massachusetts, United States
Show Abstract5:30 PM - QQ2.9/AA5.9
The Effect of Na Content on the Electrical Properties of Polycrystalline Na0.7Ga4.7Ti0.3O8 (x~0.7).
Jake Amoroso 1 2 3 , Doreen Edwards 1 2 3
1 , Alfred University, Alfred, New York, United States, 2 , New York State College of Cermaics, Alfred , New York, United States, 3 , Kazuo Inamori School of Engineering, Alfred , New York, United States
Show AbstractNew Presenting AuthorTues 11/28AA5.9/QQ2.94:30 - 4:45 pmThe Effect of Na Content on the Electrical Properties of Polycrystalline. Doreen D. Edwards
5:45 PM - QQ2.10/AA5.10
New Developments in Fluoride and Oxyfluoride Structural Chemistry.
Philip Lightfoot 1 , Nicholas Stephens 1 , Anil Jayasundera 1 , David Aldous 1
1 , University of St Andrews, St Andrews United Kingdom
Show AbstractThe development of the solid state chemistry of fluorides and oxyfluorides has lagged significantly behind that of the corresponding oxides. This is partly due to the more difficult and hazardous synthetic conditions generally required. Recently, milder methods of synthesising novel fluoride-based materials have come to the fore, both using relatively high-temperature solid state methods, and also through the increased use of solvothermal methods. We have recently been exploring the scope for preparing novel fluoride-based materials using organically-templated hydrothermal reactions. Our interests in functional materials lie in the areas of optical activity, ferroelectricity, magnetism and luminescence. In each case, the exploitation of fluoride rather than oxide-based systems may have advantages. Our recent exploratory work in this field has produced more than fifty novel compounds and structure types This talk will focus on the structural chemistry and preliminary physical property measurements of these systems, including reduced vanadium oxyfluorides, rare-earth fluorides and d0 metal oxyfluorides.
QQ3: Poster Session I
Session Chairs
Wednesday AM, November 29, 2006
Exhibition Hall D (Hynes)
9:00 PM - QQ3.11
Phase Stabilization in Hafnia-Ceria Nanoparticles as a Function of Annealing Environment and Particle Size.
Joan Raitano 1 , Sarbajit Banerjee 1 , Yu-Ming (Henry) Hung 1 2 , Chih-Hsin Lu 1 , Dae In Kim 1 , Lihua Zhang 3 , Feng Zhang 1 4 , Irving Herman 1 , Syed Khalid 5 , Jonathan Hanson 6 , Siu-Wai Chan 1
1 Materials Science and Engineering, Columbia University, Seaford, New York, United States, 2 , Infion, Tapei Taiwan, 3 Center for Functional Nanomaterials, Brookhaven National Laboratory, Upton, New York, United States, 4 , Headway Technologies, Milpitas, California, United States, 5 National Synchrotron Light Source, Brookhaven National Laboratory, Upton, New York, United States, 6 Department of Chemistry, Brookhaven National Laboratory, Upton, New York, United States
Show Abstract9:00 PM - QQ3.12
New Synthesis Method of the Sr2Fe (Mo1-xRex)O6±z (0.0 < x < 0.8) System by Acrylamide Sol-gel in Microwave.
Elizabeth Chavira 1 , Selene Rodriguez 1 , Leticia Banos 1 , Jose Guzman 1 , Carmen Vazquez 1
1 Materia Condensada y Criogenia, UNAM - IIM, Mexico Mexico
Show Abstract9:00 PM - QQ3.13
Self-cleaning Anti-reflection Coatings with Anti-fogging Properties from Layer-by-Layer Assembled Nanoparticles.
Daeyeon Lee 1 , Robert Cohen 1 , Michael Rubner 2
1 Chemical Engineering Department, MIT, Cambridge, Massachusetts, United States, 2 Department of Materials Science and Engineering, MIT, Cambridge, Massachusetts, United States
Show AbstractA self-cleaning anti-reflection (AR) coating with anti-fogging properties has been fabricated using the layer-by-layer deposition of positively charged titanium oxide (TiO2) nanoparticles and negatively charged silicon dioxide (SiO2) nanoparticles. Robustness of the SiO2/TiO2 nanoparticle multilayer films can be dramatically improved by calcinating the films at a high temperature of 550 °C. This calcination process fuses the nanoparticles together and also improves the adhesion of the coatings to glass. The composition of these composite coatings was determined by a simple method based on ellipsometry without making any assumptions about material properties (i.e., refractive index). The composition of SiO2, and TiO2 determined using this method were approximately 90 and 10 wt. %, respectively. These coatings can suppress the reflection of light from glass substantially. Glass transmits approximately 91% of light in the visible region due to reflection of light at air-glass interfaces; however, by applying these coatings onto both sides of a glass element, transmission can be increased to above 99 % in the visible region. These coatings are superhydrophilic due to the presence of nanopores. Superhydrophilicity of the coatings prevents formation of light scattering condensed water droplets on glass surfaces and results in anti-fogging properties. In addition, due to the presence of TiO2 nanoparticles which are photocatalytic, these coatings can “self-clean” or oxidize organic contaminants under UV irradiation. The combination of the three properties mentioned above makes these coatings extremely attractive for various applications including coatings on automobile windshields, windows in high rise buildings, and glass covers on solar cell panels.
9:00 PM - QQ3.14
Room-temperature Aqueous Synthesis of Metal Oxide Nanosheets and Nanoflakes through Biomimetic Approach in Association with Organic Polymers.
Yuya Oaki 1 , Hiroaki Imai 1
1 Department of Applied Chemistry, Keio University, Yokohama Japan
Show Abstract9:00 PM - QQ3.15
Fabrication of Layered Niobium Oxysulfide and Investigation of Structural and Elemental Composition.
Kazuyoshi Izawa 1 , Shintaro Ida 1 , Ugur Unal 1 , Yasumichi Matsumoto 1
1 , Kumamoto University, Kumamoto Japan
Show Abstract9:00 PM - QQ3.16
Luminescent Sol-gel Coatings Based on YVO4:Eu Nanoparticles.
Anne-Laure Penard 1 , Thierry Gacoin 1 , Jean-Pierre Boilot 1
1 , Laboratory of Condensed Matter Physics, Palaiseau France
Show AbstractFunctional coating on glasses has been largely developed using current technologies such as sputtering techniques (PVD, CVD…). These techniques are restricted to class of oxides which can be manufactured at crystallization temperature compatible with the thermal stability of glass substrates. Nevertheless, a large class of functional oxides are fully crystallized at high temperature (i.e. >800°C). An alternative route involves assembling of perfectly individualized crystallized mixed oxide nanoparticles. For instance, nanophosphors, i.e. luminescent nanocrystals can lead to original specific applications such as electroluminescent devices, integrated optics or biological labels. We present here some results concerning the assembling of rare earth oxide nanophosphors in transparent luminescent devices for applications in integrated optics. This firstly requires the development of liquid-phase syntheses to prepare size-controlled, monodisperse and bright nanoparticles. Rare earth doped nanoparticles (YVO4:Eu) were obtained as an aqueous suspension of nanoparticles (60 nm) through a simple co-precipitation of precursors salts in water, as described previously.1 This suspension exhibits a strong red emission under UV excitation with a quantum yield of about 20% and an emission lifetime of 0.7 ms. Different molecules were tested to preserve the dispersion state of the suspension with a high volume fraction of nanoparticles (i.e. > 30 g/L). Thin films were then deposited on glass substrates by spin-coating starting from the optimized suspension with a concentration of 50 g/L and using a sol-gel type binder. The amount binder has to be determined in order to obtain crack free films with optimized emitting properties and thickness. Final films were obtained after a thermal treatment, either classical, at temperatures below 400°C, or at higher temperatures, achieved with a rapid thermal annealing (RTA) equipment. The evolution of the luminance properties was studied as a function of different experimental parameters: chemical nature of the dispersant, amount of binder as well as of the thermal treatment performed the thickness of the film and the excitation wavelength. 1 A. Huignard et al., Chem. Mat. 12, 1090 (2000) ; A. Huignard et al., Chem. Mat. 14, 2264 (2002)
9:00 PM - QQ3.18
Silicate Garnet Phosphors for Solid State Illumination.
Anant Setlur 1 , William Heward 1 , Yan Gao 1 , Alok Srivastava 1 , Gopi Chandran 2 , Shankar Venugopal 2
1 , GE Global Research, Niskayuna, New York, United States, 2 , GE Global Research, Bangalore India
Show AbstractThe majority of LED based lamps use blue LEDs in combination with RE3Al5O12:Ce3+ garnet phosphors that downconvert the LED radiation into yellow light. The allowed 4f1→4f05d1 absorption transition of Ce3+ strongly absorbs blue radiation while the 4f05d1→4f1 emission transition can have a quantum efficiency near unity. While such lamps can have efficiencies that approach compact fluorescent lamps (~60 lumens/W), these lamps have correlated color temperatures (CCTs) that are too high (bluish-white lamp color) for general illumination purposes. This is due to the lack of red emission intensity in typical RE3Al5O12:Ce3+ garnet phosphors. While modifications of these phosphors can give redder emission bands, these phosphors typically have lower efficiencies compared to commercial garnet phosphors. Consequently, new phosphor development is necessary for market penetration of high efficiency lighting sources.This paper will describe an expansion in garnet crystal chemistry to make phosphors that can meet many of the necessary color and efficiency requirements for general illumination lighting. These phosphors have RE3+ and alkaline earth ions in the dodecahedral sites and Si4+ and/or Ge4+ occupying all of the tetrahedral sites in the garnet structure. Compared to previous RE3+ silicate garnets where hydrothermal synthesis is required, these garnets are made under ambient pressure conditions allowing for straightforward scale-up and potential implementation. We will focus upon the crystal chemistry of the pure silicate garnets, since the Ce3+ quantum efficiency is significantly higher in these phosphors versus materials that contain Ge4+. The regions for silicate garnet phase formation with regard to dodecahedral and octahedral site occupation will be described and their effect on the Ce3+ luminescence will be discussed. Generally, these phosphors are not phase pure (as determined by x-ray diffraction) with apatite and RE2SiO5 impurities. However, they can have high quantum efficiencies under blue (440-475 nm) LED excitation. Suitable modifications of the dodecahedral and octahedral sites lead to phosphors that cover a significant portion of the entire visible spectrum (emission peaks from 510-605 nm) including efficient red phosphors that can enable general illumination light sources. Specifically, the silicate garnet Lu2CaMg2Si3O12:Ce3+ has a red emission maximum of ~605 nm vs. ~560-570 nm for typical Al3+ garnets with a comparable quantum efficiency to these commercial materials. We will discuss the LED lamp performance of this phosphor as well as the fundamental reasons behind the changes in the Ce3+ emission color with phosphor composition.This work was partially supported by the U.S. Department of Energy through contract# DE-FC26-04NT41956 and by GELcore. However, any opinion, findings, conclusions or recommendations expressed herein are those of the authors and do not necessarily reflect the views of the Department of Energy.
9:00 PM - QQ3.19
Magnetic Properties of Vanadium Oxide Nanorods, Nanotubes and Their Prototype Compounds.
Natasha Chernova 1 , Chris Jacobs 1 , Megan Roppolo 1 , Chunmei Ban 1 , M. Stanley Whittingham 1
1 Institute for Materials Research, State University of New York at Binghamton, Binghamton, New York, United States
Show AbstractVanadium oxide nanotubes (VONTs), VO2.4[C12H28N]0.31.0.56H2O, were prepared using hydrothermal method and ion exchanged with BuLi and LiI. Vanadium oxide nanorods were synthesized by hydrothermal treatment of electrospun precursors. The compounds were characterized by x-ray diffraction, TGA, TEM, FTIR; magnetic properties were studied using SQUID magnetometer. VONTs show a spin gap which is well described by the model of magnetic dimers with antiferromagnetic (AF) exchange [1]. Isolated V4+ ions are present in this compound; their amount corresponds to the number of tetrahedral vanadium sites in the structure. Upon ion exchange with BuLi the amount of isolated V4+ is preserved, but the increase of magnetic susceptibility typical for spin-gap behavior becomes less pronounced and does not fit to the AF dimer model. No signs of significant increase of the magnetic V4+ fraction upon reaction of VONTs with BuLi is found from the magnetic properties. No hysteresis is found in the magnetization curve as opposed to earlier report [1]. Vanadium oxide nanorods with the structure related to delta V4O10 also show a large spin gap of 560 K. About 12.5% of V4+ is found in this compound analyzing the spin-gap behavior with the dimer model. Small amount (about 1%) of paramagnetic impurities is present in the nanorods. Synthesis and characterization of a prototype compound with the same vanadium oxide layer as in VONTs, but not scrolled is underway. The work is supported by the National Science Foundation through grant DMR 0313963.[1] L. Krusin-Elbaum, D. M. Newns, H. Zeng, V. Derycke, J. Z. Sun and R. Sandstrom, Nature 431, 627 (2004).
9:00 PM - QQ3.2
Synthesis and Characterization of PtW Alloy Nanoparticles for Proton Exchange Membrane Fuel Cells.
Liufeng Xiong 1 , Ting He 1
1 , Honda Research Institute, Columbus, Ohio, United States
Show AbstractProton exchange membrane fuel cells (PEMFCs) are attractive power sources due to their high energy conversion efficiency, low pollutant emissions and high power density. However, the sluggish kinetics of oxygen reduction reaction (ORR) at the cathode, the high cost of membrane and precious metal electrocatalysts, and the durability impede the wide application of PEMFCs. PtM (M = Fe, Co, Ni, or Cu) binary alloys have been extensively studied as cathode electrocatalysts in PEMFCs and show enhanced catalytic activity for ORR in comparison with Pt catalyst. Recent stability studies on these electrocatalysts, however, showed that they are not stable in PEMFC operating conditions.[1-2] Therefore, the synthesis of stable and more active oxygen reduction electrocatalyst for PEMFCs will be of great interest. PtW film exhibits high activity for ORR and good stability according to our previous study. [3] In this study, nanosized PtW alloy particles with well controlled particle size and structure were synthesized by various synthesizing methods. The morphology, structure and catalytic activity for ORR in acid electrolyte were characterized by various analytic and electrochemical techniques. The effect of synthesis conditions on the particle size and the relationship between composition and structure were also investigated. [1] T. R. Ralph and M. P. Hogarth, Platinum Met. Rev., 46, 3 (2002). [2] J. Xie, D. L. Wood III, D. M. Wayne, T. A. Zawodzinski, P. Atanassov, R. L. Borup, J. Electrochem. Soc., 152, A104 (2005). [3] E. Kreidler, L. Minor, L. Xiong and T. He, Electrocatalysis (Eds. G. Brisard, R. Adzic, V. Birss and A. Wieckowski), The Electrochemical Society, Pennington, NJ, Vol 11, 222 (2005).
9:00 PM - QQ3.20
Hexaniobate Tubes as Precursors to Nanotubular Nb2O5 and KNbO3.
Yoji Kobayashi 1 , Thomas Mallouk 1
1 Department of Chemistry, The Pennsylvania State University, University Park, Pennsylvania, United States
Show AbstractPotassium hexaniobate (K4Nb6O17) is one of the few relatively well-studied oxides which, upon exfoliation, rolls up into scrolls almost quantitatively with monodisperse length (~200 nm) and diameter (20 nm). The scrolls have high surface area (~300 m2/g) and a wall thickness of 5 nm. Here, we present the transformation of H4Nb6O17 scrolls into Nb2O5 and also potentially KNbO3 tubes of similar dimensions via ion-exchange and dehydration reactions. Nanotubular Nb2O5 is currently being tested as a catalyst support. KNbO3 tubes may exhibit unusual ferroelectric transition temperatures due to size effects.
9:00 PM - QQ3.21
Aqueous Precipitation Synthesis of Silicate-substituted Tricalcium Phosphate.
Iain Gibson 1 2 , Iain Massie 1 , Jan Skakle 1
1 Department of Chemistry, University of Aberdeen, Aberdeen United Kingdom, 2 School of Medical Sciences, University of Aberdeen, Aberdeen United Kingdom
Show Abstract9:00 PM - QQ3.23
Silicon Carbide Thin Films - via inexpensive Sol-Gel Route to High Quality Semiconductor Coatings.
Bettina Friedel 1 , Siegmund Greulich-Weber 1
1 Department of Physics, University of Paderborn, Paderborn Germany
Show Abstract9:00 PM - QQ3.25
Optimizing Performance of Electrochemical Actuators Based on Rechargeable Lithium Battery Technology.
Timothy Chin 1 , Yukinori Koyama 1 , Yet-Ming Chiang 1
1 Materials Science and Engineering, MIT, Cambridge, Massachusetts, United States
Show Abstract9:00 PM - QQ3.26
Structure - Property Relations in Aurivillius Layered Perovskites.
Neil Hyatt 1 , Andrew Giddings 1 , Joe Hriljac 2
1 Department of Engineering Materials, The University of Sheffield, Sheffield United Kingdom, 2 School of Chemistry, The University of Birmingham, Birmingham United Kingdom
Show AbstractFerroelectric layered perovskites of the Aurivillius family have recently attracted attention for use in non-volatile Ferroelectric Random Access Memory (FRAM) devices, in which digital information is stored in the switchable spontaneous polarisation state of the ferroelectric component. In structural terms, the family of Aurivillius phases, formulated Bi2An-1BnO3n+3, may be considered as being composed of a regular intergrowth of [Bi2O2]2+ fluorite-type and [An-1BnO3n+1]2- perovskite-type layers, where A is a large 12-co-ordinate cation and B a 6-co-ordinate cation with a d0 electron configuration. Here, the structure - property relations of several Aurivillius phases will be presented. Typically, these materials show a series of complex structural phase transitions, at high temperature, associated with the ferroelectric – paraelectric phase transition. The sequence of observed phase transitions has been the source of considerable controversy and debate. We demonstrate that the sequence of phase transitions observed in n = 2 Aurivillius phases may be understood by a model that embodies competition between bond-length mismatch and spontaneous polarisation, in the context of the ferroelectric and structural phase transition of Bi3Ti1.5W0.5O9 investigated by variable temperature high resolution neutron diffraction. We also present a comprehensive investigation of the crystal structure and dielectric response of the Aurivillius oxide-fluoride Bi2TiO4F2 and discuss the relationship between anion disorder, octahedral tilting and possible ferroelectric behaviour in this system. Solid state 19F Nuclear Magnetic Resonance spectroscopy indicated considerable O/F disorder over the anion sites of the Ti(O,F) 6 octahedra in this material, whereas the anion site of the Bi2O2 layer appeared to be exclusively occupied by oxygen. Bond valence sum calculations provided confirmation of this O/F distribution, fluorine occupation of the anion site in the Bi2O2 layer resulted in considerable under-bonding of the Bi cation. High resolution neutron diffraction demonstrated significant tilting of the Ti(O,F) 6 octahedra in Bi2TiO4F2, however, octahedral tilting was not co-operative, possibly a consequence of the O/F disorder over the anion sites of the octahedra. We propose that a further consequence of O/F disorder and non co-operative octahedral tilting in Bi2TiO4F2 is suppression of ferroelectric behaviour, as demonstrated by a.c. impedance spectroscopy. Finally, we present the first detailed study of the high pressure crystal chemistry of a ferroelectric Aurivillius phase, Bi4Ti3O12, by combined high pressure X-ray powder diffraction and Raman spectroscopy. This material undergoes an apparent pressure induced orthorhombic – tetragonal phase transition above 7.0 GPa.
9:00 PM - QQ3.28
Observation of First-Order Fano Asymmetry in Raman Spectra of SrTiO3 and CaxSr1-xTiO3 Perovskite Nanocubes.
Sarbajit Banerjee 1 2 , Dae Kim 1 2 , Yuanbing Mao 3 , Richard Robinson 1 2 , Stanislaus Wong 3 4 , Irving Herman 1 2
1 Materials Research Science and Engineering Center, Columbia University, New York, New York, United States, 2 Department of Applied Physics and Applied Mathematics, Columbia University, New York, New York, United States, 3 Department of Chemistry, Stony Brook University, Stony Brook, New York, United States, 4 Materials Science Department, Brookhaven National Laboratory, Upton, New York, United States
Show Abstract9:00 PM - QQ3.29
Multiscale Modeling of Charged Defects.
Amit Samanta 1 , Clemens Foerst 2 , Ju Li 1 , Sidney Yip 2
1 Department of Materials Science and Engineering, Ohio State University, Columbus, Ohio, United States, 2 Department of Nuclear Science and Engineering and Department of Materials Science and Engineering , Massachusetts Institute of Technology, Cambridge, Massachusetts, United States
Show Abstract9:00 PM - QQ3.3
Interlayer Charge Conversion Through Intercalation of Polycations into a Synthetic Swelling Mica.
Hideo Hata 1 , Yoji Kobayashi 1 , Thomas Mallouk 1
1 Chemistry, The Pennsylvania State University, University Park, Pennsylvania, United States
Show AbstractIn order to develop a new kind of layered host material that can intercalate anionic substances, poly(diallyldimethylammonium chloride) (PDDA) with high (<100,000) and low (8500) molecular weights were intercalated into synthetic sodium fluortetrasilisic mica. In both cases, PDDA could coil up and create cationic sites within the interlayer galleries of the polysilicate. The degree of polymer coiling and excess cationic charge depended on the loading of the PDDA in the host solid. The conformational change of PDDA with increasing loading was supported by powder X-ray diffraction (XRD) data as well as by calculations of Gibbs adsorption free energy through fitting experimental adsorption isotherms, in which two or more stages with different adsorption free energies were found. The surface layer charge conversion from anionic to cationic was also directly confirmed by zeta-potential measurements. Next, in order to quantify the anion accepting ability of the nano-composite, the encapsulation of a bulky acidic blue dye (Brilliant Blue FCF) was studied. The anionic dye was successfully encapsulated into the cationic interlayer spaces. This electrostatic interaction between the dye and cationic host surface was confirmed by the symmetric vibration band shift of the sulfonate group of the dye in FT-IR spectra. The amount of this blue dye accomodated could be controlled by changing the loading of PDDA within the layer. From XRD measurements, the dye-polyelectrolyte-clay nano-composites possessed two kinds of layers, and the acidic dye was site-selectively intercalated into the layers in which the PDDA polycations were coiled. This site-selective adsorption is explained by a structural model in which the original clay has domains of layers with higher and lower charge densities.
9:00 PM - QQ3.30
Information-Driven Exploration of Crystal Chemistries using Performance Based Criteria
Kim Ferris 1 , Bobbie-Jo Webb-Robertson 1 , Dumont Jones 2
1 , pacific northwest national laboratory, richland, Washington, United States, 2 , proximate technologies, llc., columbus, Ohio, United States
Show Abstract9:00 PM - QQ3.31
Synthesis and Structure Analysis of Li1.25Co0.75O2 as Cathode Material For Lithium Ion Battery
Hailong Chen 1 , Clare Grey 1 , Lihua Zhang 2
1 Department of Chemistry, State University of New York at Stony Brook, Stony Brook, New York, United States, 2 Center for Functional Nanomaterials, Brookhave National Lab, Upton, New York, United States
Show Abstract9:00 PM - QQ3.32
Fundamentals and Applications of Visible-Light Photocatalyst.
Takeshi Ohwaki 1 , Takeshi Morikawa 1 , Koyu Aoki 1 , Ken-ichi Suzuki 1 , Tadayoshi Itoh 1 , Ryoji Asahi 1 , Yoshitaka Nakano 1 , Yukihiro Oota 2 , Yutaka Mitsubori 2
1 , TOYOTA Central R&D Labs., Inc., Aichi Japan, 2 , TOYOTA TSUSHO Co., Nagoya Japan
Show Abstract9:00 PM - QQ3.4
Bio-Inspired Calcium Carbonate Core-Shell Particle.
Yi-Yeoun Kim 1 , Sherman Cox 1
1 Discovery Research, Specialty Minerals Inc, Bethlehem, Pennsylvania, United States
Show AbstractFormation of hollow particles and core-shell particles has earned significant attention for many applications, such as controlled release of drugs, and protection of bioactive materials from harsh conditions.In this report, we present a bio-inspired process to create hollow (core-shell) calcium carbonate particles under aqueous conditions. The approach employs a Polymer-Induced Liquid-Precursor (PILP) process. We demonstrate that the mineral nanocluster precursor forms as calcium carbonate shell that subsequently solidifies and crystallizes. In the system used here, highly acidic polyelectrolytes and core substrates, which are adopted from organic matrices found in natural systems, are employed to template a mineral shell. Core templates can be used for the deposition of the mineral nanoclusters, as well as a platform for loading functional materials. Both the calcium carbonate mineral shell and the soft core template are biocompatible and biodegradable, which is required for the safety of biomaterial processes and applications.
9:00 PM - QQ3.5
High Spin Transition Metal Clusters with Redox Active Ligands Derived from TTFs.
Lahcene Ouahab 1
1 Chemistry, CNRS-Universite de Rennes1, Rennes France
Show AbstractDeveloppement of molecular electronics depends strongly on the developpement of functional molecules and molecule-based materials. Therefore, current trends in this last field include nanoscience, functional single molecules such as single molecule magnets, single chain magnets and single molecule conductor, and multifunctional materials. In particular, designing molecule-based materials, which possess synergy or interplay between two or more properties such as electrical conductivity with magnetism or spin cross-over …, is currently a challenging target and it has been attracting great interests from chemists and physicists for both application to devices or for fundamental science. Preparation of paramagnetic transition metal complexes where the redox active ligands such TTFs are coordinated to spin carrier is a very promising alternative to achieve conducting (or superconducting) magnets through interaction between d spins and mobile electrons.1 We present in this contribution a new route for the synthesis of homometallic and heterometallic polynuclear transition metal complexes as well as their crystal structures, cyclic voltametry and magnetic properties.2 The first trinuclear complexes of this kind are shown in the figure and it constitutes a first step towards high spin single molecules with redox active ligands. Current target is the study the behaviour and properties of this kind of nonoscale molecules (~4nm) on surfaces.1.L. Ouahab, T. Enoki, Eur. J. Inorg. Chem., 931, (2004)2.K.S. Gavrilenko, S.V. Punin, O. Cador, S. Golhen, L. Ouahab, V.V. Pavlishchuk, J. Am. Chem. Soc., 127, 12246 (2005).
9:00 PM - QQ3.7
Photoluminescence Spectral Change in Self-Assembled Layered Titanate Oxide Intercalated with Eu3+.
Shintaro Ida 1 , Ugur Unal 1 , Kazuyoshi Izawa 1 , Chikako Ogata 1 , Yasumichi Matsumoto 1
1 Graduate School of Science and Technology, Kumamoto University, Kumamoto Japan
Show Abstract9:00 PM - QQ3.8
Biomimetic Synthesis of Inorganic Nanoparticles on Micropatterned Polymer Templates.
Jamie Ford 1 , Jun Hyuk Moon 1 , Shu Yang 1
1 Materials Science and Engineering, University of Pennsylvania, Philadelphia, Pennsylvania, United States
Show AbstractBiominerals exhibiting the hierarchical organization of nano- to macroscopic features possess remarkable optical, structural and mechanical properties that have inspired the development of new hybrid materials. Nature’s control over these biomineralization processes requires the intimate interaction between inorganic molecules and organic templates that control and direct the size, shape, morphology and location of the deposited inorganic materials. We have mimicked the biomineralization process with a synthetic polymer template that allows for the controlled, selective, and fast growth of inorganic materials in predetermined patterns. Poly(ethylenimine) (PEI) was grafted onto photopatterned hydrogel films of poly(2-hydroxyethylmethacrylate-co-acrylic acid), PHEMA-co-PAA, to direct the deposition of silica and titania nanoparticles from sol-gel condensations of silicic acid (Si(OH)4) and titanium bis(ammonium lactate) dihydroxide (TALH), respectively, at room temperature and mild pH conditions. We have studied the effects that PEI molecular weight, solution pH, and PEI grafting methods have on the size, morphology and growth mechanisms of the nanoparticles. The integration of top-down and bottom-up fabrication approaches provide a promising new route to synthesize complex hybrid materials over multiple length scales.
Symposium Organizers
Ram Seshadri University of California-Santa Barbara
Joseph W. Kolis Clemson University
David B. Mitzi IBM T. J. Watson Research Center
Matthew J. Rosseinsky The University of Liverpool
QQ4: Porous and Nanostructured Materials I
Session Chairs
Wednesday AM, November 29, 2006
Grand Ballroom (Sheraton)
9:00 AM - **QQ4.1
Routes to Multi-functional Nanocomposites.
Christopher Murray 1 , Jeffrey Urban 1 2 , Elena Shevchenko 1 3 4 , Dmitri Talapin 1 3 , Stephen O'Brien 4
1 , IBM, T. J. Watson Research Center, Yorktown Heights, New York, United States, 2 Dept. Chemistry, Michigan State University, East Lansing, Michigan, United States, 3 The Molecular Foundry, Lawrence Berkeley National Labs, Berkeley, California, United States, 4 Dept Applied Physics & Applied Mathematics, Columbia University, New York, New York, United States
Show Abstract9:30 AM - QQ4.2
Microstructured Optical Fibers as New Nanotemplates for High Pressure CVD.
Neil Baril 1 4 , John Badding 1 4 , Vankatraman Gopalan 2 4 , Pier Sazio 3 , Thomas Scheidemantel 5 4 , Bryan Jackson 1 , Dong-Jin Won 2 4 , Adrian Amezcua Correa 3 , Chris Finlayson 3
1 Chemistry, The Pennsylvania State University, University Park, Pennsylvania, United States, 4 Center for Nanoscale Science, The Pennsylvania State University, University Park, Pennsylvania, United States, 2 Materials Science and Engineering, The Pennsylvania State University, University Park, Pennsylvania, United States, 3 Optoelectronics Research Centre, University of Southampton, Southampton United Kingdom, 5 Physics, The Pennsylvania State University, University Park, Pennsylvania, United States
Show AbstractSolid state chemists have long been interested in templated growth of materials using many approaches. The resulting materials have been useful in areas as diverse as photonics and catalysis. Microstructured optical fibers form a new class of nanotemplates that can have sub 50 nm pores that are meters to kilometers long. We have developed a high pressure microfluidic chemical process that allows for conformal deposition of materials within microstructured optical fibers to form the most extreme aspect ratio semiconductor nanowires known. The wires can be spatially organized with respect to each other at dimensions down to the nanoscale for device applications because the microstructured optical fibers templates can be designed with almost any desired periodic or aperiodic pattern. Many if not most of the chemistries used for conventional CVD can be adapted for this process. The resulting materials should enable a large range of scientific and technological applications.Sazio et al. Science 311, 1583 (2006)
9:45 AM - QQ4.3
Directed Assembly of Divalent Ligand-Coated Nanoparticles into One-Dimensional Chains.
Gretchen DeVries 1 , Oktay Uzun 1 , Brenda Long 1 , Francesco Stellacci 1
1 DMSE, MIT, Cambridge, Massachusetts, United States
Show AbstractNanoparticles tend to spontaneously aggregate into ordered two- and three-dimensional assemblies, but achieving one-dimensional structures of nanoparticles is less straightforward. Since the properties of nanoparticles depend not only on the characteristics of each individual nanoparticle but also on its interactions with neighboring particles, a method to manipulate and control the directional interactions between nanoparticles is an essential step toward the development of nanoparticle-based devices. Ligand-coated metal nanoparticles are particularly promising for this aim, both because the ligands affect the physical properties of the nanoparticles and because the ligands can be used as handles for self-assembly of the particles. In this work, we demonstrate directed assembly of mixed-ligand metal nanoparticles into one-dimensional chains by taking advantage of ordered domains that spontaneously form in the ligand shell. As a result of this molecular-level ordering, two diametrically opposed defect points are generated that can be functionalized with a third type of molecule, creating a divalent nanoparticle that can interact directionally with other molecules or nanoparticles. For example, by placing carboxylic acid terminated molecules at the defect points and reacting the newly divalent nanoparticles with diamine terminated molecules, linear chains of nanoparticles joined by peptide bonds can be generated. Kinetic studies of the place exchange process at the two defect points indicate that these are unique sites in the ligand shell with significantly higher reactivity than at other sites on the nanoparticle. Furthermore, these nanoparticle chains can be dried and assembled into free-standing macroscopic films that possess unique mechanical and electrical properties.
10:00 AM - QQ4.4
Synthesis of Pure Rutile Nanotubes.
Dominik Eder 1 , Ian Kinloch 1 , Alan Windle 1
1 Department of Materials Science and Metallurgy, University of Cambridge, Cambridge United Kingdom
Show Abstract10:15 AM - QQ4.5
From Single Molecules to Nanoscopically Structured Functional Materials.
Wolfgang Tremel 1 , Muhammad Tahir 1 , Helen Therese 1 , Nicole Zink 1 , Ute Kolb 1 , Patrick Theato 1 , Werner Müller 2 , Heinz Schröder 2
1 Chemistry, Universität Mainz, Mainz Germany, 2 Medicine, Universität Mainz, Mainz Germany
Show AbstractThe covalent attachment of functional ligands such as photo-or redox active molecular compounds to inorganic nanoparticle surfaces is an important step in the design of new functional materials. These applications, however, require designated molecules to be immobilized on the nanoparticle. A variety of molecular surface chemical linkages have been devised for oxide surfaces based on siloxane, phosphonate or catecholate functional groups. Oxide nanoparticles have a versatile surface chemistry, which we have utilized for the functionalization with organic chromophores, polymers, biological markers, and proteins which are able to catalyze further reactions (e.g. the formation of metal nanoparticles.Besides metal oxides and carbon nanotubes metal chalcogenide nanoparticles, firstly reported by Tenne and co-workers in 1992, have opened up an exciting new area of research into nanomaterials with sheet structures, which – unlike single layer graphite – are multiple layer structures. These MQ2 (Q = S, Se, Te) species, termed inorganic fullerenes (IF) and inorganic nanotubes (NT), are akin to carbon nanotubes in that they exhibit analogous electronic properties and an extraordinary mechanical strength. Since a functionalization by direct anchoring of organic ligands to the sulfur surface of the sandwich-type metal dichalcogenide particles is not possible, a special functionalization strategy based on a transition metal cation with a high sulfur affinity was devised. The coordination sphere of this metal cation is blocked on one side with an umbrella-type chelating ligand carrying a linker group with additional functionalities, whereas the other part of the coordination sphere remains open for docking to the sulfur layer. We have used scorpionate-type tetradentate ligands attached to a reactive block-copolymer, where the two vacant coordination sites of transition metal ions (Co2+, Ni2+) are used for the binding to the chalcogenide surface. The resulting functionalized IF-MoS2 and NT-WS2 nanoparticles can be dispersed in water and organic solvents, and anchored to the sidewalls of oxide nanowires. This interlinking of IF-MoS2 particles is an attractive alternative for surface coatings of ceramics with IF-MoS2 lubricants. The functionalization strategy can be extended for the covalent binding of (i) fluorescent organic molecules, (ii) molecular clusters and (iii) macromolecules or proteins to the sidewalls of chalcogenide nanoparticles. The functionalization strategy is extremely versatile and offers new opportunities for optoelectronic and/or biological applications of metal chalcogenide nanoparticles. Furthermore, it allows the arrangement of inorganic nanoparticles for a bottom-up assembly of hierarchical structures, e.g. by introducing suitable linker units as functional molecules. The control of the surface chemistry of the chalcogenide nanoparticles paves a new avenue from single molecules to nanoscopically structured functional materials.
10:30 AM - QQ4:PorNan
BREAK
11:00 AM - **QQ4.6
Nanostructured Crystals:Unique Hybrid Semiconductors with Systematically Tunable Structures and Properties
Jing Li 1 , Xiaoying Huang 1 , Wooseok Ki 1
1 Chemistry and Chemical Biology, Rutgers University, Piscataway, New Jersey, United States
Show AbstractAn exciting and promising area of current material research concerns chemistry and physics of inorganic-organic hybrid structures. While inorganic materials are well known for their structural rigidity and stability, superior electronic, magnetic, optical, and transport properties, organic molecules have excellent flexibility, processability, structural diversity and can be made at relatively low cost. Incorporation of the two components into a single structure will not only result in combination and enhancement of these useful properties but also likely lead to new phenomena and new functionality. We have recently developed a unique class of hybrid nanostructured crystals that are composed of sub-nanometer-sized II-VI semiconductor motifs (inorganic component) and acyclic mono- and di-amines (organic component). These hybrid materials possess a number of improved/enhanced properties over their parent bulk semiconductors, including broad band-gap tunability, high absorption coefficients, and large carrier diffusion lengths, all desirable for optoelectronic applications such as photovoltaics and solid state lighting. More significantly, they exhibit very strong quantum confinement effect (QCE) as a result of the internal structure rather than particle size, and their nanoproperties can be systematically tuned by modifying the structure and dimensionality of the inorganic motifs.
11:30 AM - QQ4.7
Solution Processing of Metal Chalcogenide Phase-Change Materials
David Mitzi 1 , Simone Raoux 2 , Robert Shelby 2 , A. Schrott 1 , Matthew Copel 1 , Andrew Kellock 2 , Jean Jordan-Sweet 1
1 , IBM T. J. Watson Research Center, Yorktown Heights, New York, United States, 2 , IBM Almaden Research Center, San Jose, California, United States
Show AbstractInterest in phase-change materials (PCMs) has flourished recently, as a result of emerging technological applications including, most notably, commercially-available rewritable optical media (e.g., CD-RW, DVD-RW, DVR) and the development of nonvolatile phase-change memory (PRAM). Generally, PCMs are deposited using vacuum-based techniques such as sputtering or thermal evaporation, which are not very amenable to high-throughput processing at a reasonable cost. In this study, we demonstrate the solution-based processing of several chalcogenide-based phase-change materials, including KSb5S8, using a version of our recently reported hydrazine-precursor approach (D. B. Mitzi et. al., Nature 428, 299, 2004). The process involves dissolving the metal chalcogenides or elemental metals and chalcogen in hydrazine at room temperature, spin-coating the solution onto a substrate, followed by a short low-temperature anneal. PCM films with thicknesses in the range of 10-100 nm have been deposited with peak processing temperatures of 225 - 350 C. The solution-deposited films have been analyzed using temperature-dependent x-ray diffraction, Rutherford Backscattering Spectrometry (RBS), Medium Energy Ion Scattering (MEIS), Scanning Electron Microscopy (SEM) and pulsed laser testing to examine chemical, structural, morphological and phase-change properties. While spin-coated KSb5S8 yields a repeatable amorphous-crystallization transition and a reasonably high crystallization temperature, the crystallization kinetics appear too slow to enable this material to be useful for high-data-rate transfer applications (contrary to prior expectations based on bulk differential scanning calorimetry measurements). However, the hydrazine-based approach is expected to be more generally applicable to the deposition of a variety of other chalcogenide-based PCMs.
11:45 AM - QQ4.8
Solvothermal Syntheses of Electrically Conductive Films
David Kisailus 1 , Thomas Stanford 1 , Tina Salguero 1 , Jennifer Zinck 1
1 Sensors and Materials Lab, HRL Laboratories LLC, Malibu, California, United States
Show AbstractIn this work we describe a low temperature process, which produces RuO2 thin films on stainless steel substrates. These coatings exhibit extremely low contact resistances (<50mΩ-cm2). This solvothermal process demonstrates enhanced mass transport of nutrient to the substrate surface enabling a coating uniformity. High resolution SEM reveals that these uniformly coated nanostructured films, less than 150nm thick, are comprised of 90-120 nm RuO2 nanocrystals that appear faceted. Contact resistance measurements before and after chemical modification indicate the film’s high electrical conductivity is maintained.We are attempting to extend these synthetic routes towards other oxide materials. Potential uses of this low-temperature solvothermal route for nanostructured films are also under investigation for optical and electronic applications, and sensors.
12:00 PM - QQ4.9
Nanoparticles in Lysine-Silica Mixtures.
Tracy Davis 1 , John Krohn 1 , Michael Tsapatsis 1
1 Chemical Engineering & Materials Science, University of Minnesota, Minneapolis, Minnesota, United States
Show AbstractAs in the directed growth of porous synthetic silicates (i.e., zeolites), the formation of biosilica proceeds along a pathway directed by an organic species. For example, long chain polyamines and silaffin proteins have been determined to direct the growth of biosilica in diatoms (1-3). In contrast to the hydrothermal conditions used in zeolite synthesis, those present during the formation of biosilica structures include near-neutral pH and ambient temperatures. Furthermore, the organic molecules of biomineralization are believed to serve as both catalyst and structure directing agent (SDA) unlike in zeolite synthesis where the organic (e.g., tetrapropylammonium (TPA)) serves solely as a template.Despite recent efforts to duplicate the hierarchical structures of biosilicas through laboratory methods, synthesis of these structures remains an elusive goal. In order to meet this end, the mechanism by which silicates are formed in nature must be better understood, and the contribution of each of the protein components should be elucidated (4). In a recent study by Cha et al. (5), the protein attributed with directing the polycondensation of biosilica in the sponge Tethya aurantia was mimicked by using diblock copolypeptides; tetraethylorthosilicate (TEOS) was used as the silica source. Results suggest that poly-L-lysine possesses a low activity for TEOS hydrolysis and condensation. In other studies (1, 2), Sumper and Kroger have shown that polyamine groups likely catalyze the biosilica reaction in diatoms. Motivated by these reports, we performed a study on aqueous lysine-silica mixtures, a system that serves as a simple model to study the role of amino acids in biosilica formation. Through in situ characterization of these mixtures by cryogenic transmission electron microscopy and small angle X-ray scattering, we can show for the first time that silica nanoparticles (c.a. 5 nm) are present in aqueous lysine-silica mixtures. These nanoparticles are similar in size and shape to those present in “clear” sols of TEOS and TPA from which the zeolite, silicalite-1 is formed. The colloidal species of these clear sols have been shown to evolve to silicalite-1 crystals and to participate in growth (6) at room temperature. It follows that the presence of silica nanoparticles in biomimetic lysine-silica mixtures may be of significant consequence. References 1. N. Kroger, S. Lorenz, E. Brunner, M. Sumper, Science 298, 584 (2002).2. M. Sumper, N. Kroger, J. Mater. Chem. 14, 2059 (2004).3. M. Sumper, S. Lorenz, E. Brunner, Angew. Chem. Int. Ed. 42, 5192 (2003).4. D. Belton, G. Paine, S. V. Patwardhan, C. C. Perry, J. Mater. Chem. 14, 2231 (2004).5. J. N. Cha, G. D. Stucky, D. E. Morse, T. J. Deming, Nature 403, 289 (2000).6. T. M. Davis et al., Nature Materials 5, 400 (2006).
12:15 PM - QQ4.10
How Molecules Turn Into Solids?
Arunachalam Ramanan 1 2 , M Stanley Whittingham 2
1 Chemistry, Indian Institute of Technology, Delhi, New Delhi , Delhi, India, 2 Chemistry and Materials Research Center, Binghamton University, Binghamton, New York, United States
Show AbstractCrystal engineering of metal organic framework (MOF) based materials is of contemporary interest due to its potential applications in the area of catalysis, gas separation and storage. Hydrothermal and solvothermal are popular chemical routes for the synthesis of such materials. The diversity of their structural frameworks is commonly attributed to the choice of metal, its ability to occur in different coordination geometry and multidentating nature of organic ligands. However, no one has proposed a logical mechanism in terms of chemical events that triggers a particular structural organization. A careful structural analysis of a number of MOFs synthesized in the presence of aromatic amines and acids show that the 'true building blocks' are not really recognized! We postulate a simple mechanism for the formation of MOFs starting from a soluble metal complex that is formed as soon as the reactants are mixed in solution. We demonstrate with examples how this metal complex preassembles with templating organic molecules through well-defined supramolecular interactions. Condensation of this assembly through elimination of water or solvent will lead to the final architecture. Our intuitive approach can rationalize almost all architectures of MOFs reported in the literature. We strongly believe that a better understanding of the mechanism of the formation of solids from solution will eventually allow for designing 'a tailor-made material' with a specific structure and desirable properties.
QQ5: Porous and Nanostructured Materials II
Session Chairs
Wednesday PM, November 29, 2006
Grand Ballroom (Sheraton)
2:30 PM - **QQ5.1
A General, Non-aqueous Route Towards Oxidic Nanoparticles and their Controlled Alignment.
Markus Antonietti 1 , Markus Niederberger 1
1 Department of Colloid Chemistry, MPI of Colloids and Interfaces, Potsdam Germany
Show AbstractNon-aqueous sol-gel routes turned out to be very powerful to synthesize a whole variety of previously hardly accessible nanoparticles with low polydispersity and high crystallinity. The system include binary and ternary oxidic materials, but also nitrides. The particle size is adjusted by the choice of solvent and reaction conditions.Addition of special organic stabilizers, so-called assemblers, resulted in site specific adsorption onto the nanoparticles and their controlled assembly towards superstructures with sometimes astonishing symmetry and order. Some applications of those nanostructures are also discussed, for instance in electrochemistry, for novel sensors, and in ultrathin ceramic coatings.
3:30 PM - QQ5.3
Synthesis of Porous Materials via Multiscale Templating Approaches: Emulsions, Nanoparticles, Supercritical Fluids, and Directional Freezing.
Andrew Cooper 1 , Haifei Zhang 1
1 Chemistry, University of Liverpool, Liverpool United Kingdom
Show Abstract3:45 PM - QQ5.4
Intercalation of Organic Molecules into Vanadium (IV) Benzenedicarboxylate: Adsorbate Structure and Selective Absorption of Organo-sulfur Compounds.
Xiqu Wang 1 , Lumei Liu 1 , Allan Jacobson 1
1 Chemistry, University of Houston, Houston, Texas, United States
Show AbstractThe capacity and selectivity of nanoporous materials in absorption and in separation of molecular mixtures depend on specific interactions between the host frameworks and removable guest species and in some cases the degree to which the structure of the host lattice can relax as molecular species are intercalated. The classical zeolite frameworks are relatively rigid and exhibit little deformation upon loading and unloading of various guest species. On the other hand, intercalation into layered structures leads to expansion of the interlayer separation because of the very weak interlayer bonding, and can lead to complete exfoliation of the layers.Flexibility without loss of crystallinity is expected for structures containing rigid building blocks linked by relatively deformable hinge-like units. Examples of framework flexibility have been found in a number of metal-organic frameworks (MOFs). Among them, a group of compounds MOHBDC (M = V, Cr, Al) and VOBDC first reported by Férey and coworkers, based on chains of trans corner-sharing octahedra cross-linked by 1,4-benzene dicarboxylate (BDC), show remarkable framework flexibility upon removal or absorption of guest species. Sorption studies of these metal organic frameworks have focused on H2 adsorption, but some additional studies of the absorption of CO2 and CH4 have been described. In the present work, we have synthesized single crystals of [VOBDC](H2BDC)0.71 1 directly. After removal of the guest acid molecules by heating 1 in air, we have shown that the VOBDC structure is sufficiently flexible to undergo single-crystal-to-single-crystal transformations upon absorption of various guest molecules enabling the details of the guest structure, framework-guest interactions, and framework deformations to be determined from single crystal X-ray diffraction data. Furthermore, we have observed rapid and highly selective gas phase absorption of sulfur containing compounds from methane by VOBDC.
4:00 PM - QQ5:PorNan
BREAK
4:30 PM - **QQ5.5
Hierarchical Structuring and Functionalization of Templated Porous Carbon.
Andreas Stein 1 , Zhiyong Wang 1 , Fan Li 1 , Nicholas Ergang 1 , Dan Yu 1 , Justin Lytle 1
1 Department of Chemistry, University of Minnesota, Minneapolis, Minnesota, United States
Show AbstractPorous carbon materials enjoy widespread use in applications as sorbents, filters, catalyst supports, electrodes, sensors, and many other applications. Recently new synthetic methods have been developed to prepare carbon structures with designed porosities and architectures. Using hard and soft templates, microporous, mesoporous or macroporous carbon can be synthesized with either periodic or disordered pore structures. When multiple templating techniques are employed, hierarchical pore-structuring is also possible. In this presentation, we will discuss the use of colloidal crystal templating, block-copolymer templating and nanocasting from porous silica preforms to prepare glassy carbon monoliths with photonic crystal structure (periodic arrays of interconnected macropores with diameters of a few hundred nanometers) and monoliths with both macropores and mesopores that are a few nanometers in diameter. Such monoliths can provide a basis for complex assemblies, including multifold interpenetrating structures. Just as surface functionalization of porous silica materials has benefited potential applications, controlled functionalization of porous carbon materials will be useful to modify their surface and bulk properties. We will present methods of attaching molecular modifiers, polymer layers or oxide nanoparticles to the surface of porous carbon, as well as a process of producing porous glassy carbon/graphitic carbon nanocomposites. The effects of surface modification on properties including pore texture, mechanical strength, electronic conductivity and capacity for lithiation will be evaluated.
5:00 PM - QQ5.6
Condensable Amphiphiles as Templates for the Construction of Novel Porous Vanado-Silicate Solids.
Vassilios Binas 1 , Pantelis Trikalitis 1
1 Department of Chemistry, University of Crete, Iraklio Greece
Show AbstractVanadium oxide-based catalysts are used in the manufacture of important chemicals (e.g. sulfuric acid, phthalic anhydride) and is the most important metal used in metal oxide catalysis. Most of these catalysts consist of a vanadium oxide phase deposited on the surface of an oxide support SiO2, Al2O3, TiO2 and ΖrO2. A large number of relevant studies have shown that the nature of the vanadium oxide phases is influenced only by the surface coverage. Neither the preparation method nor the nature of the support affects the local coordination environment of supported vanadium oxides. However, both parameters greatly affect the amount of vanadium oxide which can be deposited. The catalytic performance of these systems in terms of yield and selectivity is highly dependent on the amount of isolated (SiO)3-V=O three-legged species. Therefore, new methods that allow one-pot synthesis of ordered and porous silicate solids with high content of isolated (SiO)3-V=O species are highly desirable.We developed a novel strategy for the construction of porous vanado-silicate materials utilizing a condensable amphiphile as template. For the first time it is demonstrated that these molecules can be used as structure directing agents for the development of porous mixed-metal oxide solids. This versatile molecule contains a condensable silane group –Si(OMe)3, a quarternized nitrogen (–N+R2-) and a long aliphatic carbon chain C18. The presence of these characteristic functionalities renders these molecules suitable for both sol-gel and self-assembly or supramolecular chemistry. All products characterized with a variety of techniques including powder XRD, TEM, SEM, TGA, IR, RAMAN and surface area BET measurements. The final solids exhibit high surface area (>800 m2/g) and very narrow pore size distribution of hexagonally ordered pores with 20Å diameter. Most important, we found that the amount of isolated (SiO)3-V=O species in the final products can be easily controlled by adjusting the pH and is significantly higher than that in materials synthesized under the same experimental conditions utilizing common surfactant molecules as templates such as CnTABr.Following the same approach we have developed other than Vanadium transition metal oxide mesoporous silica-based solids such as MoOx-SiO2 and WOx-SiO2, thus demonstrating the general applicability of the method.
5:15 PM - QQ5.7
Spontaneous Transformations in the Solid State: Towards Porous and Biphasic Materials.
Eric Toberer 1 , Ram Seshadri 1
1 Materials, UCSB, Santa Barbara, CA, California, United States
Show Abstract5:30 PM - QQ5.8
3-D Photonic Band Structure Engineering in Self-Assembled Macroporous Photonic Crystals
Jeremy Galusha 1 , Kaycee Carter 1 , Michael Bartl 1
1 Department of Chemistry, University of Utah, Salt Lake City, Utah, United States
Show AbstractOwing to their unique potential of non-classical photon manipulation and confinement photonic crystals have emerged over the last years as one of the most promising concepts of next generation optical device configurations such as photonic chips and all-optical integrated circuits. Among the various photonic crystal structures 3-D ordered macroporous materials fabricated by fast and inexpensive colloidal crystal templating/sol-gel infiltration techniques have gained much interest in recent years. While most of these colloidal assembly-based methods result in so-called inverse opal photonic crystals (fcc air sphere lattice in a titania matrix) with a fixed photonic band structure, we present here a fabrication technique that allows to controllably modify the simple inverse opal (fcc air-sphere) structure. By applying directional pressure along main crystal axes of the opal template under controlled temperatures, we are able to induce selective deformation of the opaline colloidal crystal template before infiltration with titania precursor. We will demonstrate that due to the strong structure-property relationship in photonic crystals such selective deformations/modifications in the crystal structure result in strongly modified photonic band structures and hence optical properties. Furthermore, experimental data will be accompanied by extensive theoretical modeling and band structure calculations to confirm the experimental results and to predict new photonic structures with engineered and property-optimized photonic band structures.
5:45 PM - QQ5.9
High Surface Area Inorganic Nitrides and Carbides.
Stefan Kaskel 1
1 , Department of Inorganic Chemistry, Dresden Germany
Show AbstractNon-oxide materials such as inorganic nitrides and carbides have been extensively studied for the application as dense ceramics due to their high mechanical and thermal stability. However, only little attention has been paid to develop a rational design of non-oxide porous materials with high accessible surface area suitable for catalytic applications. Highly porous silicon nitride-based materials (Si3N4)[1] as well as GaN materials [2] with specific surface areas up to 1000 m2g-1 are obtained using a non-oxide sol-gel process. The pore size may be adjusted in the micropore range (1-2 nm) as well as in the mesopore regime (5-9 nm) using different precursors and amines as templates. The design of single-source molecular precursors also allows to obtain ternary materials such as silicon aluminium nitride based solids [3]. Main group element nitrides are promising catalysts in solid-base catalyzed reactions. Transition metal nitrides such as TiN, Mo2N and VN with high specific surface area are obtained using molecular precursors or via nitridation of oxide-based foams [4]. They have catalytic properties related to those of noble metals (Pt) and can be used in dehydrogenation reactions with applications in the production of propene and in hydrogen storage. A new concept for the design of porous non-oxide materials is “nanocasting” using solid mesoporous templates such as SBA-15 via chemical vapour or polymer infiltration and subsequent etching of the porous matrix. In this way ordered mesoporous SiC materials with specific surface areas up to 800 m2g-1 are available [5].[1] P. Llewellyn, S. Kaskel, in Handbook of Porous Solids, F. Schüth, K. S. W. Sing, J. Weitkamp (Ed.), Wiley, VCH, Weinheim, 2002, 2063-2086; S. Kaskel, K. Schlichte, B. Zibrowius, Phys. Chem. Chem. Phys. 2002, 4, 1675-1681; S. Kaskel, K. Schlichte, J. Catal. 2001, 201, 270-274; S. Kaskel, D. Farrusseng, K. Schlichte, Chem. Commun. 2000, 2481-2482; [2] G. Chaplais, K. Schlichte, O. Stark, R. Fischer, S. Kaskel, Chem. Commun. 2003, 730-731; G. Chaplais, S. Kaskel, J. Mater. Chem. 2004, 14, 1017-1025. [3] S. Kaskel, G. Chaplais, K. Schlichte, Chem. Mater. 2005, 17, 181-185; S. Kaskel, C. W. Lehmann, G. Chaplais, K. Schlichte and M. Khanna, Eur. J. Inorg. Chem. 2003, 6, 1193-1196.[4] K. Schlichte, S. Kaskel, J. Mol. Catal. A 2004, 208, 291-298; S. Kaskel, K. Schlichte, G. Chaplais, M. Khanna, J. Mater. Chem. 2003, 13, 1496-1499; B. Bogdanovic, M. Felderhoff, S. Kaskel, A. Pommerin, K. Schlichte, F. Schüth, Adv. Mater. 2003, 15, 1012-1015; P. Krawiec, P. L. De Cola, R. Gläser, J. Weitkamp, C. Weidenthaler, S. Kaskel, Adv. Mater. 2006, 18, 505-508.[5] P. Krawiec, S. Kaskel, Chem. Mater. 2004, 16, 2869-2880; P. Krawiec, D. Geiger, S. Kaskel, Chem. Commun. 2006, 2469-2470.
QQ6: Poster Session II
Session Chairs
Thursday AM, November 30, 2006
Exhibition Hall D (Hynes)
9:00 PM - QQ6.1
Structure and Stability of Ceria and Titania Nanoparticles.
Srujan Rokkam 1 , Anter El-Azab 1 2 , Michael Dyer 1
1 Mechanical Engineering, Florida State University, Tallahassee, Florida, United States, 2 School of Computational Science, Florida State University, Tallahassee, Florida, United States
Show Abstract9:00 PM - QQ6.10
Defect Structure Behaviour In Metal Halides.
Mark Levy 1 , Robin Grimes 1
1 Materials Department, Imperial College London, London United Kingdom
Show AbstractMany materials, when subjected to an electric field, will polarise to oppose that field. One contribution to the polarization involved the movement of some ions from their equilibrium lattice positions. When the field is removed, the ions gradually relax back to their original positions. If the field is imposed at a high temperature and the material is subsequently quenched in the field, this displacement polarization can be “frozen-in”, implying an energy barrier against relaxation. When this material is then slowly heated, this polarization will be removed once ions have gained sufficient thermal energy to overcome the energy barrier. This process is called the dielectric relaxation and can be monitored as a current.It has been suggested that zinc fluoride doped with lithium exhibits considerable anisotropy in its dielectric properties, specifically, a strong relaxation effect in [001] but significantly less in [100] and [110].Defects associated with LiF solution in ZnF2. have been investigated using atomistic scale computer simulation techniques. These defects are important in controlling a number of key materials properties. In particular here, the symmetry of the solution defect has been considered, which, in turn affects the mechanism behind the experimentally observed anisotropic dielectric relaxation of lithium doped ZnF2.The relative energies for the solution of LiF indicate the formation of a split interstitial defect structure. By analysis of the lithium migration and cluster binding energies, the experimentally observed dielectric relaxation processes are better understood. Also, the simulations were consistent with a much lower solution limit than was previously assumed experimentally. Consequently, it seems that the original material was far from equilibrium. This is a major consideration, as many materials property determinations require that the material be at equilibrium. Thus, the observed anisotropy is a consequence of these non equilibrium defects.
9:00 PM - QQ6.11
Site-specific Nucleation and Kinetics in Hierarchical Nanosyntheses of ZnO
Z. Ryan Tian 1 , Tierui Zhang 1 , Wenjun Dong 1 , Mary Keeter-Brewer 1 , Quincy Anderson 1 , Roland Njabon 1 , Jay Kasbohm 1
1 Chemistry/Biochemistry, University of Arkansas, Fayetteville, Arkansas, United States
Show Abstract9:00 PM - QQ6.12
Pulsed Laser Deposited Oxide Green Emitting Thin Film Phosphors : Optimization of Growth Conditions.
Mahidanna Rao 1 2 , P. Thiyagarajan 1 2 , M. Kottaisamy 2
1 Physics, Indian Institute of Technology, Chennai, TamilNadu, India, 2 Materials Science Research Centre, IITM, Chennai, Tamilnadu, India
Show Abstract9:00 PM - QQ6.13
Synthesis of Tailor-Made Ceramic Nanomaterials.
Bernadette Hernandez-Sanchez 1 , Timothy Boyle 1 , Luke Brewer 1
1 Advanced Materials Laboratory, Sandia National Laboratories, Albuquerque, New Mexico, United States
Show AbstractThe syntheses of novel routes to ceramic nanomaterials are being heavily researched due to their potential widespread applications, ranging from electronics to biotechnology. As the demand for these nanomaterials increase, flexible synthetic routes that can accommodate the applications criteria will be required. Therefore, we are interested in developing novel precursors such as metal alkoxides (M(OR)x) and organometallics (M(R)x) to meet the needs of generating tailor-made nanomaterials. By exploring the materials chemistry of nanoparticle synthesis, recent results from our laboratory indicate that the choice of precursor selection may have an effect on the final crystalline phase, properties, or morphology of the ceramic nanomaterials. To exploit this hypothesis, we have used solution precipitation and solvothermal routes to generate perovskites(ABO3), naturally occurring florescent minerals (NOFs), magnetic oxides, and other ceramic materials. A brief overview of a series of well characterized and structurally diverse series of metal neo-pentoxide (OCH2CCMe3, ONep), aryloxide (OC6H4R-2,6 where R = CHMe3 (oBP), Me2 (DMP), CH(Me2)2 (DIP)), and mesityl precursors (where mesityl = 2,4,6-Me3C5H2) used to synthesize tailor-made ceramic nanomaterials along with the final properties characterization for the resulting nanoparticles will be presented. This work supported by the Department of Energy, Office of Basic Energy Sciences and the United States Department of Energy under contract number DE-AC04-94AL85000. Sandia is a multi-program laboratory operated by Sandia Corporation, a Lockheed-Martin Company, for the United States Department of Energy.
9:00 PM - QQ6.14
A Fundamental Investigation of Erbium Dihydride.
Ryan Wixom 1 , Dwight Jennison 1
1 Nanostructure and Semiconductor Physics, 1112, Sandia National Laboratories, Albuquerque, New Mexico, United States
Show Abstract9:00 PM - QQ6.15
Surface-mediated Growth of Oriented Anatase Titania Nanostructured Arrays
Donghai Wang 1 , Jun Liu 1 , Qisheng Huo 1 , Zimin Nie 2 , Rick Williford 2
1 Interfacial Science and Engineering, Pacific Northwest National Laboratory, Richland, Washington, United States, 2 Material Chemistry and Surface Research, Pacific Northwest National Laboratory, Richland, Washington, United States
Show AbstractAnatase TiO2 is an important functional material with a wide range of applications. In connection with the wide applications such as chemical sensing, photocatalysis, optical emission, and energy conversion and storage such as photovoltaics, batteries, and capacitors, anatase TiO2 arrays with well-controlled nanostructures, crystallographic planes and favorable orientation are very desirable due to their open structure, high surface area and porosity, favorable orientation that may provide enhanced device performances. In this presentation, we report a new class of anatase TiO2 nanostructured arrays with controlled nanocrystalline morphology and crystallographic orientation via slow oxidative hydrolysis on substrates with specific surface charge. The nanostructured anatase TiO2 arrays have been characterized using XRD, TEM, SEM, UV-vis, Raman spectroscopy and other techniques. In the growth of the nanostructured arrays, surface charge promotes oriented nucleation of anatase TiO2. Thus well-defined oriented nanocrystals are obtained in presence of capping ligands, eventually form a continuous oriented array. The nanocrystalline building blocks can be tuned from octahedral pyramidal nanocrystals to truncated pyramidal nanocrystals. Well-defined octahedral pyramidal nanocrystals with sharp tips are oriented with [001] axis preferably perpendicular to the substrate. The unique structure of octahedral pyramidal nanocrystals in the nanostructured TiO2 arrays lead to anatase (101) surface as the most accessible surface, which may be used in specific site-selective catalysis. Truncated pyramidal nanocrystals, which are close to equilibrium shape of anatase TiO2, are also oriented with [001] axis preferably vertical to the substrate showing (001) stage planes at the top of each nanocrystal. Because of unique chemical, physical and optical properties of TiO2, we expect this new class of TiO2 arrays are of great interest for sensor, photovoltaic, and other applications.
9:00 PM - QQ6.17
Synthesis and Struture Determination of 3D Indium Oxide-Organic Frameworks.
Marie Vougo-Zanda 1 , Xiqu Wang 1 , Allan Jacobson 1
1 Chemistry, University of Houston, Houston, Texas, United States
Show Abstract9:00 PM - QQ6.18
Structure and Bonding in SnWO4, PbWO4 and BiVO4: Lone Pairs vs. Inert Pairs
Matthew Stoltzfus 1 , Patrick Woodward 1 , Ram Seshadri 2 , Jae-Hyun Park 1 , Bruce Bursten 1
1 , The Ohio State University, Columbus , Ohio, United States, 2 Materials Department , University of California Santa Barbara, Santa Barbara, California, United States
Show AbstractThree ternary oxides, SnWO4, PbWO4, and BiVO4, containing p-block cations with ns2np0 electron configuration, so called lone pair cations, have been studied theoretically using density functional theory and UV-Visible diffuse reflectance spectroscopy. The computations reveal significant differences in the underlying electronic structures that are responsible for the interesting and varied crystal chemistry of the lone pair cations. The filled 5s orbitals of the Sn2+ ion interact strongly with the 2p orbitals of oxygen, which leads to a significant destabilization of symmetric structures (scheelite and zircon) favored by electrostatic forces. The destabilizing effect of this interaction can be significantly reduced by lowering the symmetry of the Sn2+ site to enable the antibonding Sn 5s – O 2p states to mix with the unfilled Sn 5p orbitals. The calculations show that this interaction produces a localized, non-bonding state at the top of the valence band that corresponds closely with the classical notion of a stereoactive electron lone pair. In compounds containing Pb2+ and Bi3+ the relativistic contraction of the 6s orbital reduces its interaction with oxygen, effectively diminishing its role in shaping the crystal chemical preferences of these ions. In PbWO4 this leads to a stabilization of the symmetric scheelite structure. In the case of BiVO4 the interaction of the Bi 6s orbital with oxygen is further diminished. However, the increased effective nuclear charge also stabilizes the Bi 6p orbital energy enabling a second order Jahn Teller (SOJT) distortion through mixing with the nonbonding O 2p states found at the top of the valence band. While the SOJT distortions observed for both Sn2+ and Bi3+ ions have similar structural consequences, the role of the valence shell s-orbital is significantly diminished in the case of Bi3+.
9:00 PM - QQ6.19
Improvements in the Ordering Kinetics, Quality Factor and Sintering of Ba((Ni0.13Zn0.87)1/3Ta2/3)O3 Microwave Dielectric Ceramics
Niti Yongvanich 1 , Peter Davies 1
1 Materials Science and Engineering, University of Pennsylvania, Philadelphia, Pennsylvania, United States
Show AbstractThe complex perovskite Ba(Zn1/3Ta2/3)O3 (BZT) with its extremely low dielectric loss (high Q), relatively high dielectric constant and near-zero temperature coefficient of resonant frequency, has been utilized extensively as a dielectric resonator for microwave-based satellite communications. The highest Q values for BZT are observed in well sintered ceramics with a high degree of 1:2 cation order on the B-sites; however, their processing is severely complicated by the volatilization of ZnO during sintering which can severely degrade the dielectric response. Therefore, lower sintering temperatures and shorter sintering times are highly desirable to minimize the volatilization and reduce the processing costs. In this study, we have investigated the potential formation of non-stoichiometric solid solutions of Ba((Ni0.13Zn0.87)1/3Ta2/3)O3 (BNZT) and their effect on the 1:2 ordering, Q, and the sintering. The effect of different sintering environments was also examined. Non-stoichiometric compositions of BNZT were prepared and investigated along eight different pseudo-binary directions (BaO, Ni0.13Zn0.87O, Ta2O5, (Ni0.13Zn0.87)Ta2O6, Ba3Ta2O8, Ba3(Ni0.13Zn0.87)O4, Ba8(Ni0.13Zn0.87)Ta6O24 and BaTa2O6). Evidence for a limited range of non-stoichiometry was found for all eight directions; although these ranges can be extremely narrow, in certain directions they have a very large impact on the ordering kinetics, densification and Q. The highest Q values and the lowest sintering temperatures are situated along the (Ni1/3Zn0.87)Ta2O6 and BaTa2O6 directions where dense, single-phase ceramics were obtained after sintering for 12 hours at 1400°C; for comparison temperatures in excess of 1500°C are required to sinter stoichiometric BNZT. The sintering temperature could be reduced further by at least 25 °C by conducting the processing in a ZnO-rich vapor atmosphere. Prolonged post-sintering annealing was found to be effective in obtaining large cation-ordered domains and the resultant ceramics yielded Q values in excess of 13,000 at 9-10GHz. The effect of the non-stoichiometry and sintering environment on the ordering kinetics, dielectric properties and microstructures will be discussed.
9:00 PM - QQ6.2
The Influence of Nanoparticle Characteristics on the Assembly and Disassembly of Nanoparticle-Block Copolymer Mesostructured Hybrids.
Scott Warren 1 2 , Francis DiSalvo 2 , Ulrich Wiesner 1
1 Dept. of Materials Science & Engineering, Cornell University, Ithaca, New York, United States, 2 Dept. of Chemistry & Chemical Biology, Cornell University, Ithaca, New York, United States
Show Abstract9:00 PM - QQ6.20
Synthesizing Phosphors through Microwave Process.
Chris Fang 1 , Dinesh Agrawal 1 , Joan Coveleskie 2 , Chung-nin Chau 2 , James Walck 2 , Rustum Roy 1
1 Materials Research Institute, The Pennsylvania State University, University Park, Pennsylvania, United States, 2 , OSRAM Sylvania Inc., Towanda, Pennsylvania, United States
Show AbstractVarious Lamp phosphors, including [Ca10(PO4)6(Cl,F):Sb:Mn], (Y,Eu)2O3, BaMgAl10O17:Eu, and (La,Ce)PO4:Ce:Tb, with or without flux, have been synthesized by a microwave processing technique in a multimode microwave furnace operating at 2.45 GHz. The microwave-synthesized phosphors were comprehensively characterized for particle size, specific surface area, brightness, and luminescence. Although most properties of the microwave-synthesized phosphors were comparable to that of the conventional products, the kinetics of the phosphor synthesis was substantially enhanced in the microwave processing. As a result, the soaking time at the final temperature was reduced by up to 90% compared to a conventional process. In addition, the required synthesis temperature was also lowered by 100-200C in microwave process, compared to the conventional process for these lamp phosphors. Certain improved property was also observed in some microwave synthesized samples. The mechanism and advantages of microwave process for the lamp phosphor synthesis through solid-state reaction are addressed.
9:00 PM - QQ6.21
Synthesis of Polycrystalline Sn and SnO2 Electrodes Containing Wire Morphologies
Clara Santato 1 2 , Carmen López 1 , Kyoung-Shin Choi 1
1 Department of Chemistry, Purdue University, West Lafayette, Indiana, United States, 2 , Institute for the Study of Nanostructured Materials, Bologna Italy
Show Abstract Sn and SnO2 have received great attention due to their potential for use in energy production and sensing devices. Both Sn and SnO2 are recognized as high capacity anode materials for Li ion batteries, while SnO2 has also been extensively studied for photocatalytic and photoelectrochemical applications. The bandgap of SnO2 (Eg = 3.6 eV) is too large to utilize the visible portion of the solar spectrum, but its low lying conduction band makes it possible to efficiently accept photogenerated electrons from other semiconductors when used in multi-component systems (i.e. SnO2/ZnO, SnO2/TiO2), which can significantly reduce the rate of electron-hole recombination. The efficiencies of Sn and SnO2 electrodes in these applications are largely dependent on their nano- and mico-scale structures. These structures not only determine the surface areas available for desired interfacial reactions but also affect the overall charge transport properties in the electrodes. Among various polycrystalline morphologies, the wire morphology is of strategic importance, because this morphology can significantly minimize the randomness of the charge carriers’ pathway and guide them more efficiently to the back contact. When properly doped, SnO2 films with wire morphologies may also offer ideal transparent conducting substrates to assemble dye-sensitized solar cells and photoelectrochemical cells that can significantly increase the junction areas between photoelectrodes and the back contact. In this presentation, we report a new electrochemical synthetic condition to prepare Sn films containing wire morphologies that does not require soft or hard templates. Compositions of plating media and deposition conditions that enhance the growth of wires will be discussed in detail. The Sn films can be converted to SnO2 films by thermal oxidation while still preserving the wire morphology. Photoelectrochemical properties of SnO2 films will also be discussed in conjunction with their micro- and nano-scale structures.
9:00 PM - QQ6.22
Electrochemical Morphogenesis of Micron-Size Cu2O Crystals
Matthew Siegfried 1 , Kyoung-Shin Choi 1
1 Department of Chemistry, Purdue University, West Lafayette, Indiana, United States
Show AbstractCrystals with different shapes consist of different atomic arrangements on the surface (e.g. surface termination, symmetry, interatomic distances) which directly affect a material’s reactivity and stability. Therefore, the ability to systematically tune the shape of a material would be invaluable in adjusting its properties and elucidating shape-property relationships. The two main processes that determine a crystal’s shape are habit formation and branching growth. In this presentation we demonstrate how these two processes can be independently and freely regulated in the electrocrystallization of Cu2O from a copper nitrate medium. Crystal habit can be regulated by introducing additives that preferentially adsorb onto specific crystallographic planes. We will discuss in detail the effect and efficiencies of various additives (e.g. sodium dodecyl sulfate, Cl-, NH4+) in stabilizing {100}, {111} and {110} surfaces of Cu2O crystals. While crystal habit mainly depends on the composition of the plating solution, the degree of branching can be independently regulated by controlling the reaction rate or overpotential. We have identified two different mechanisms of branching growth during Cu2O deposition. One is diffusion limited branching that appears with high overpotential and the other is reduction limited branching that is stabilized when using a low overpotential. These two different mechanisms will be comparatively discussed in this presentation. Combining the ability to control habit and branching growth with the flexibility of electrodeposition in controlling crystal growth, we demonstrate how numerous novel crystal architectures can be assembled by rationally designing growth conditions and a growth chronology.
9:00 PM - QQ6.23
The Effect of Inorganic and Organic Modifiers on Brushite Crystal Growth
Jennifer Giocondi 1 , Christine Orme 1 , Xiangying Guan 2 , George Nancollas 2 , John Hoyer 3
1 Chemistry and Materials Science, Lawrence Livermore National Laboratory, Livermore, California, United States, 2 Dept. of Chemistry, SUNY Buffalo, Buffalo, New York, United States, 3 The Children's Hospital of Philadelphia, University of Pennsylvania, Philadelphia, Pennsylvania, United States
Show Abstract9:00 PM - QQ6.24
Synthesis of Doped TiO2 by the Hydrothermal Pouch Method.
Margaret Welk 1 , Evelyn Cruz 2 , Blake Simmons 2
1 Chemical and Biological Systems, Sandia National Laboratories, Albuquerque, New Mexico, United States, 2 , Sandia National Laboratories, Livermore, California, United States
Show AbstractTitanium dioxide is a well known photocatalytic material. When illuminated with UV light, an electron is excited within the TiO2, creating an electron – hole pair that can participate in catalytic reactions. In the pure anatase phase of TiO2, this phenomenon is limited to the use of UV wavelength light. Through moderate temperature hydrothermal synthesis, TiO2 doped with carbon, nitrogen, and yttrium has been synthesized. The synthesis can be modified to produce exclusively the rutile or the anatase form of TiO2. In this method, the properties of the polymer pouch are exploited to achieve controlled hydrolysis at elevated temperatures and pressures. For comparison, syntheses of anatase TiO2 were carried out at five different temperatures ranging from 100 to 200 °C. Agglomerates of TiO2 crystallites are visible by SEM. Average particle size as calculated from the powder x-ray diffraction ranges from 10 to 20 nm; the largest average particle size was found for the TiO2 synthesized at 200°C. The highest dopant levels of carbon (0.12%) and nitrogen (0.15 %) occur at a reaction temperature of 125° C, while for yttrium, the maximum (13.3%) occurs at 200°C. Doping the material shifts the adsorption edge from the UV (385 nm) to the visible light spectrum (410nm). Testing of the oxidative ability of doped TiO2 versus pure TiO2 reveals that a test dye molecule is degraded by the doped TiO2 in less than half the time of pure TiO2.Sandia is a multiprogram laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the US DOE’s NNSA, contract DE-AC04-94-Al85000.
9:00 PM - QQ6.25
Synthesis and Luminescent Property of Nanocrystalline Phosphors by Solvothermal Processes.
Chien-Yuen Tung 1 , Te-Wen Kuo 1 , Shyue-Ming Chang 1 , Teng-Ming Chen 2
1 MCL, ITRI, Hsinchu Taiwan, 2 Department of Applied Chemistry, National Chiao Tung University, Hsinchu Taiwan
Show Abstract9:00 PM - QQ6.26
The Hydrothermal Chemistry of Early Transition Metal Fluorides.
Dave Aldous 1 , Phil Lightfoot 1
1 Chemistry, St Andrews University, St Andrews, FIFE, United Kingdom
Show AbstractNew functional materials with optical and magnetic properties are our current area of research. In each case, the exploitation of fluoride rather than oxide-based systems may have advantages. Our recent exploratory work in this field, focussing on the structural chemistry and preliminary physical property measurements, will be discussed.Several novel organically templated fluorides of early transition metals have been prepared. Examples of isolated polyhedra, 1- and 2D structures will be presented. A family of oligomeric vanadium oxyfluorides, ranging from monomers to layered structures has been made. In the structure of [C6N4H22][VOF4(H2O)]2●H2O, both cis and trans variants of the [VOF4(H2O)]2- octahedral unit are observed, with the cis variant previously unreported. A new tetrameric building unit has also been created. [C6N3H20]2[V4O4F14]●2H2O displays antiferromagnetic properties at low temperatures.A new chain compound has been produced using either Cs or Rb cations as the template species. CsVOF3 and RbVOF3 consist of a stacked edge-sharing dimer to form an infinite chain (isostructural with ½ spin vanadate ladders). The same chain structure has also been synthesised with trans 1,2 bis (4-pyridyl) ethylene as the template to make [C12H12N2]0.5[VOF3]. The magnetic properties of these materials will be discussed.[C10H8N2][VF3] is the first vanadium fluoride where the organic template is bonded to the vanadium metal atom in a layered structure.
9:00 PM - QQ6.27
Surface-engineering for Porous Coordination Polymers.
Daisyke Tanaka 1 , Shigeyuki Masaoka 2 , Satoshi Horike 1 , Susumu Kitagawa 1
1 Graduate School of Engineering, Kyoto Univ., Kyoto Japan, 2 Graduate School of Science, Kyushu Univ., Fukuoka Japan
Show Abstract9:00 PM - QQ6.28
Nanoscale Modulations Formed by the Periodic Phase Separation of Li-containing Perovskites.
Beth Guiton 1 , Peter Davies 1
1 Department of Materials Science and Engineering, University of Pennsylvania, Philadelphia, Pennsylvania, United States
Show AbstractFor complex perovskites, which contain a mixture of cations on either the A- and/or the B-site, long range ordering of the different cations can be critical in mediating the functional response. For example, the ordering of La, Li and vacancies on the A-site in the (La1/2Li1/2)TiO3- (La2/3)TiO3 system leads to large reductions in their ionic conductivity. These A-site deficient, Li-containing systems can also show an unusual diffraction signature associated with a nanometer-scale modulation whose structure and chemical driving force is not yet understood. Through investigations of the corresponding (Nd1/2Li1/2)TiO3- (Nd2/3)TiO3 solid solution, we have discovered that these diffraction effects are associated with a spontaneous phase separation which leads to perfectly periodic nanodomain superlattices in two dimensions. The superlattice originates from periodically spaced square nanodomains of the Li-rich end member separated by boundaries comprising the opposite end member. In addition to these compositional interfaces the structure contains twin and anti-phase boundaries with the same periodicity; this ordering propagates in the third dimension to yield a nanoscale “checkerboard” structure which persists through the entire bulk crystal. The periodicity of the checkerboard structure can be tuned precisely by controlling the absolute composition, or relative concentrations, of the two end members. This is to our knowledge the first example of an oxide exhibiting periodic phase separation in more then one-dimension (i.e. lamellae). In contrast to self-assembled nanocrystal arrays the nanodomains in these structures are assembled via the ionic bonding of the boundary region, and as such demonstrate periodicities of extraordinary perfection, previously inaccessible to the nanometer scale.
9:00 PM - QQ6.29
Synthesis of new Dion Jacobson Layered Perovskites Incorporating Vanadyl Oxocations.
Mark Chambers 1 , Neil Hyatt 1
1 Department of Engineering Materials, The University of Sheffield, Sheffield United Kingdom
Show AbstractNew Dion Jacobson layered perovskites, Cs1-2x(VO)xLa2Ti2NbO10.nH2O and Rb1-2x(VO)xLaNb2O7.nH2O, were prepared by an ion exchange reactions between CsLa2Ti2NbO10 or RbLaNb2O7 and aqueous VOSO4, at 60oC. The ion exchanged products are deep green in colour, in comparison with the precursors which are white. In both ion exchanged products, the presence of isolated vanadyl, VO2+, oxocations cations was confirmed by the presence of a characteristic IR stretch (at ~1014cm-1) and an Electron Spin Resonance signal (at g = 1.960, X-band). Elemental analysis indicated the degree of exchange in these materials was limited to x < 0.25, resulting in up to 25% of the cation sites between the perovskite layers being vacant. Thermogravimetric analysis revealed the ion-exchanged products to be hydrated with n ~ 0.7. Dehydration of the ion exchanged phases resulted in decomposition, suggesting that the water molecules pack the vacant cation sites, thereby stabilising the structure. Rietveld analysis of X-ray powder diffraction data demonstrated that the ion exchanged phases retain the structure of their parent materials, with random substitution of vanadyl oxocations between the perovskite sheets. This was confirmed by comparison of the Raman spectra of the parent and ion exchanged materials. The vibrational modes associated with the transition metal octahedra neighbouring the interlayer gallery were found to undergo significant shifts in frequency, as a consequence of the intercalation of VO2+ oxocations and water molecules. These results demonstrate that new Dion Jacobson layered perovskites may be synthesised by ion-exchange in VOSO4 solution.
9:00 PM - QQ6.3
Crystal and Magnetic Structures of the Perovskite oxyfluorides,PbFeO2F and 0.5PbFeO2F-0.5PbTiO3.
Tetsuhiro Katsumata 1 , Hiroaki Takase 1 , Yoshiyuki Inaguma 1 , Jhon Greedan 2 , Jacques Barbier 2 , Lachlan Cranswick 3 , Mario Bieringer 4
1 Department of Chemistry, Gakushuin University, Tokyo Japan, 2 Chemistry department and Brockhouse Institute for Materials Research, McMaster University, Hamilton, Ontario, Canada, 3 CNBC, NRC, Chalk River, Ontario, Canada, 4 Department of Chemistry, University of Manitoba, Winnipeg, Manitoba, Canada
Show Abstract9:00 PM - QQ6.31
Oxidative Degradation of Atomized Iron Controlled the Nanostructure Environment.
Naveen Rawat 1 , Russel Gudyaka 1 3 , Mohit Kumar 1 , Kalathur Santhanam 1 2
1 Center For Materials Science and Engineering , Rochester Institute of Technology, Rochester, New York, United States, 3 , Delphi, Rochester, New York, United States, 2 Department of Chemistry, Rochester Institute of Technology, Rochester, New York, United States
Show AbstractTransfer toWednesday 11/29posterQQ9.29 to QQ6.31Oxidative Degradation of Atomized Iron Controlled the Nanostructure Environment. Naveen Rawat
9:00 PM - QQ6.4
Nanocrystalline Ceria-Zirconia Fluorite-Like Solid Solutions Doped with La, Pr or Gd and Promoted by Pt: Structure, Surface Properties and Catalytic Performance in Syngas Generation.
Vladislav Sadykov 1 , Natalia Mezentseva 1 , Galina Alikina 1 , Anton Lukashevich 1 , Vitalii Muzykantov 1 , Yulia Borchert 1 , Tatiana Kuznetsova 1 , Ella Moroz 1 , Dmitrii Zyuzin 1 , Vera Kol’ko 1 , Vladimir Kriventsov 1 , Vyacheslav Ivanov 1 , Aleksandr Shmakov 1 , Andrei Boronin 1 , Egor Pazhetnov 1 , Eugenii Paukshtis 1 , Vladimir Rogov 1 , Julian Ross 2 , Erhard Kemnitz 3
1 , Boreskov Institute of Catalysis SB RAS, Novosibirsk Russian Federation, 2 , Limerick University, Limerick Ireland, 3 Institute for Chemistry, Humboldt-University, Berlin Germany
Show Abstract9:00 PM - QQ6.5
Synthesis and Electrochemistry of Layered Double Hydroxide Thin Films by Layer-by-Layer Assembly Method.
Ugur Unal 1 , Ozge Altuntasoglu 1 , Shintaro Ida 1 , Yasumichi Matsumoto 1
1 Faculty of Engineering, Department of Nano Science and Technology, Kumamoto University, Kumamoto Japan
Show Abstract9:00 PM - QQ6.7
A First-Principles Study on Effects of Tin, Oxygen and Vacancy on Electronic Structures in Indium Oxide.
Ryoji Sahara 1 , Koichi Hirabayashi 1 , Hiroshi Mizuseki 1 , Takashi Nakamura 2 , Yoshiyuki Kawazoe 1
1 , Institute for Materials Research, Tohoku University, Sendai Japan, 2 , Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai Japan
Show Abstract9:00 PM - QQ6.8
Vibrational Recognition of Adsorption Sites for Carbon Monoxide Adsorbed on Platinum and Platinum-Ruthenium Surfaces using Density-functional Perturbation Theory.
Ismaila Dabo 1 , Andrzej Wieckowski 2 , Nicola Marzari 1
1 Materials, MIT, Cambridge, Massachusetts, United States, 2 Chemistry, University of Illinois Urbana Champaign, Urbana, Illinois, United States
Show AbstractWe have studied the energetic, structural and vibrational properties of carbon monoxide adsorbed on platinum and platinum-ruthenium surfaces using density-functional theory within the generalized-gradient approximation (GGA). The GGA frequency predictions for the C-O stretching mode are in excellent agreement with spectroscopic measurements. This agreement is made more remarkable by the generally-poor performance of standard exchange-correlation functionals which fail even in predicting the most stable adsorption site for CO on platinum. We discuss the excellent accuracy of density-functional theory in predicting accurate vibrational spectra while paradoxically failing in determining the correct adsorption-energy sequence.
Symposium Organizers
Ram Seshadri University of California-Santa Barbara
Joseph W. Kolis Clemson University
David B. Mitzi IBM T. J. Watson Research Center
Matthew J. Rosseinsky The University of Liverpool
QQ7: Electronic Solids
Session Chairs
Thursday AM, November 30, 2006
Grand Ballroom (Sheraton)
9:00 AM - **QQ7.1
Superconductivity in the Pyrochlore Oxides.
Zenji Hiroi 1
1 Institute for Solid State Physics, University of Tokyo, Kashiwa, Chiba, Japan
Show Abstract9:30 AM - QQ7.2
Superconductivity in Clathrates Ba24IV100 ( IV = Si and Ge ) with Rattling Motions.
Takeshi Rachi 1 , Ryotaro Kumashiro 1 2 , Hiroshi Fukuoka 3 , Shoji Yamanaka 3 , Katsumi Tanigaki 1 2
1 Physics, Tohoku University, Sendai Japan, 2 , JST-CREST, Kawaguchi Japan, 3 Applied Chemistry, Hiroshima University, Higashi-Hiroshima Japan
Show Abstract9:45 AM - QQ7.3
Investigation of the Large Negative Magnetoresistance in the Ruthenocuprate RuSr2Nd0.9Ce0.9Y0.2Cu2O10.
Abbie Mclaughlin 1 , John Attfield 2
1 Chemistry, Aberdeen University, Aberdeen United Kingdom, 2 Centre for Science at Extreme Conditions, University of Edinburgh, Edinburgh United Kingdom
Show Abstract10:00 AM - QQ7.4
Competing Interactions in the Kagome Antiferromagnet YBaCo4O7
John Mitchell 1 , Laurent Chapon 3 , Ashfia Huq 2 , Hong Zheng 1 , Paolo Radaelli 3 , Peter Stephens 4
1 Materials Science Division, Argonne National Laboratory, Argonne, Illinois, United States, 3 ISIS Facility, Rutherford Laboratory, Chilton Didcot United Kingdom, 2 Intense Pulsed Neutron Source, Argonne National Laboratory, Argonne, Illinois, United States, 4 Physics and Astronomy, SUNY Stonybrook, Stonybrook, New York, United States
Show AbstractThe mixed-valent Co2+/Co3+ compound YBaCo4O7 is built up of Kagome sheets of CoO4 tetrahedra linked in the third dimension by a triangular layer of CoO4 tetrahedra in an analogous fashion to that found in the known geometrically frustrated magnets such as pyrochlores and SrCr9xGa12-9xO19. We have undertaken a study of the structural and magnetic properties of these compounds using combined high-resolution powder neutron and synchrotron x-ray diffraction. Here we identify the role of charge-order and structural transitions in breaking geometric frustration in favor of magnetic order. We also discuss how the unique antiferromagnetic structure of this compound reveals a competition between in-plane and out-of-plane interactions. We also discuss the sensitivity of properties to oxygen content and speculate on mechanisms to 're-frustrate' the magnetic interactions.
10:15 AM - QQ7.5
Structure and Electronic Properties of Silicon and Germanium Network Polyhedra
Katsumi Tanigaki 1 3 , Takeshi Rachi 1 , Ryotaro Kumashiro 1 , Hiroshi Fukuoka 2 , Shoji Yamanaka 2
1 department of Physics, Graduate of Scinece, Tohoku University, Sendai Japan, 3 CREST, JST, Saitama Japan, 2 Department of Cemistry, Graduate School of Engineering, Hiroshima University, Hiroshima Japan
Show AbstractWhen the special conditions are constrained to the network formation in IVth group of elements like silicon and germanium, nano materials having network polyhedra are produced. Although the sp3-hybridized bonding is favored in silicon and germanium different from carbon, where both sp2- and sp3- hybridizations are realized in graphite and diamond, a new series of materials featured by the polyhedral cage frameworks including sp2-characters have been searched to date and lots of such materials, so called clathrates, have been found. In these nano materials, one of the important issues is the phonons. Because of the cluster cages and their inner spaces inside, the phonons different from the conventional lattice phonons can be taken into consideration. For instance, intra-cluster phonons are believed to play an important role for giving rise to unique electronic states and endohedral atomic phonons with showing time- and space-dependent anharmonic oscillations are thought to have exotic interactions with conduction electrons at the Fermi surfaces. The latter phonons have recently been drawing much attention in materials science and are called as rattling phonons. The rattling phonons have freedom in motion and will break the symmetry of the crystals. In this sense, in silicon and germanium clathrates, phonons are glass-like and the electrons spreading over the polyhedral networks are crystal-like. This exotic concept of phonon-glass and electron-crystal (PGEC) shows lots of possibilities of creating novel materials like good thermoelectric compounds. In this meeting, we would like to show some such experimental examples and stress on the perspective research directions of silicon and germanium nano materials with network polyhedra. The first demonstration will be electronic properties realized in silicon and germanium clathrates. We have recently made this family of compounds showing intriguing properties. One example is Ba8Si46 comprising of silicon isotopes of 28Si and 30Si [1]. In this material, cluster phonons can be varied so that electron-phonon coupling can be modified. A similar isotope network polyhedra using 29Si may lead to a unique quantum state coming from its nuclear spin states. Another example is Na16Ba8Si136 network polyhedra [2]. In this clathrate, intra-cluster phonons can be varied owing to the different combination of polyhedra of Si24 and Si28, and intriguingly this shows an electronic state showing electron localization. The other is Ba24IV100 (IV=Si and Ge) [3]. Ba24Si100 and Ba24e100 are the iso-structural crystals, but their electronic properties are very much different. We will discuss whether the rattling phonons of Ba play an important role for controlling electronic states.[1] K. Tanigaki, et al, Nature Materials, 2, 653 (2004). [2] T. Rachi, K. Tanigaki*, R. Kumashiro, J. Winter, H. Kuzmany, Chem. Phys. Letters, 409,48 (2005). [3] T. Rachi, K. Tanigaki et al., Phys. Rev. B, 72, 144504 (2005).
11:00 AM - **QQ7.6
Thermoelectric Oxides : New Compounds, Underlying Physics and Applications to Electricity Production.
Antoine Maignan 1 , Sylvie Hébert 1 , Yannick Klein 1
1 , CRISMAT, UMR 6508 CNRS/ENSICAEN, Caen France
Show Abstract11:30 AM - QQ7.7
Synthesis, Magnetic Properties and Structures of the Pillared Perovskites, La5Re2TaMO16 (M = Mn, Fe, Co, Ni).
Heather Cuthbert 1 , John Greedan 1 2 , Lachlan Cranswick 3
1 Department of Chemistry, McMaster University, Hamilton, Ontario, Canada, 2 Brockhouse Institute for Materials Research, McMaster University, Hamilton, Ontario, Canada, 3 Canadian Neutron Beam Centre, National Research Council Laboratory, Chalk River, Ontario, Canada
Show Abstract
Recently, a novel structural motif – the so-called “pillared perovskite”– has been found.The composition is Ln5M2ABO16 where Ln is a trivalent lanthanide and M, A and B are transition elements from the 3d, 4d and 5d transition series. The structure can be visualized as layers of corner-sharing metal-oxygen octahedra of composition ABO6 which are “pillared” by two edge-sharing M2O10 octahedral dimer units. The dimers link each perovskite layer through the B sites only. Families of compounds which have been investigated to date include, among others, La5Mo4O16 where Mo4+ resides on the M and B sites and Mo5+ on the A site and La5Re3BO16 with Re5+ on the M and A sites and a 3d transition metal such as Mn2+, Fe2+, Co2+ or Ni2+ on the B site. Many of these materials have interesting and unusual magnetic properties such as ferrimagnetic intralayer short range magnetic correlations and long range antiferromagnetic order at surprisingly high temperatures (160K – 200K) given the > 10Å interlayer separation.[1,2]
A new family of pillared perovskites, isostructural to the aforementioned compounds, has been made. The La5Re2TaBO16 series, where B is a 2+ transition metal ion (such as Mn, Fe, Co or Ni), replaces the magnetic Re5+ (S = 1) within the perovskite layers on the A site with diamagnetic Ta5+. Due to metal-metal bonding within the dimers, the Re5+ electrons are paired. Thus, the only magnetic ion within these compounds is the B2+ ion. By varying the B2+ ion from Mn (S = 5/2) to Ni (S = 1), the effect of the spin quantum number on the resulting magnetism of these low-dimensional compounds has been studied.
SQUID magnetometry measurements have revealed that all of these materials have a sharp feature at the approximately the same critical temperature (Tc) of their all Re analogues, La5Re3BO16. Heat capacity measurements on the Co and Ni members have also confirmed the presence of long-range magnetic order, and the assignment of Tc. Variable temperature powder neutron diffraction studies have allowed for the elucidation of the magnetic structures, and confirmed the assignment of Tc in all of these compounds. Similarities between the La5Re2TaBO16 series and other pillared perovskites (such as La5Re3BO16) will be discussed. The observation of short range ferromagnetic intralayer correlations in the Ta5+ family is difficult to understand in terms of intralayer exchange only and suggests a role for interlayer magnetic superexchange.
[1]K. V. Ramanujachary, S. E. Lofland, W. H. McCarroll, T. J. Emge, and M. Greenblatt, J. Solid State Chem. 164 (2002) 60.
[2]C. R. Wiebe, A. Gourrier, T. Langet, J. F. Britten and J. E. Greedan, J. Solid State Chem. 151 (2000) 31.; L. Chi, A. E. C. Green, R. Hammond, C. R. Wiebe, and J. E. Greedan, J. Solid State Chem. 170 (2003) 165; H. L. Cuthbert, J. E. Greedan and L. M. D. Cranswick, J. Solid State Chem. 179 (2006) 1938.
11:45 AM - QQ7.8
Chemical Control of Magnetic Properties: Comparison of Doped Barium Manganites Ba4-xAxMn3O10 (A=Sr, La, Nd).
Jan Skakle 1 , Abbie McLaughlin 1 , Mpoyi Mubumbila 1
1 Chemistry, University of Aberdeen, Aberdeen United Kingdom
Show AbstractDoped manganites and Ruddlesden-Popper (RP) phases are of much interest due to intensive interest in the colossal magnetoresitance (CMR) properties of these materials since the discovery of CMR in the La-doped RP phase Sr1.8La1.2Mn2O7by Morimoto et al. in 1996.The previously reported manganite Ba4Mn3O10 has the stoichiometry of an RP phase but has a structure containing corrugated layers of face-sharing octahedra. It contains Mn4+ and is reported to be antiferromagnetic below 80K. We have carried out a series of doping studies on this material in an attempt to manipulate the Mn4+:Mn3+ ratio and hence the magnetic properties. The resultant materials have been extensively characterised. XRD and EDX were used to give information on purity and composition, FTIR was used to check for carbonate inclusion whilst thermogravimetry and XPS were used to analyse the oxygen contents of the materials. Neutron diffraction and SQUID measurements were used to characterise the magnetic properties, and ac impedance spectroscopy gave information on the electrical properties.Isovalent substitution (Ba ↔ Sr) results in a large solid solution, but with no change in the Mn valence in the materials. At high levels, the inclusion of carbonate within the structure prevents the synthesis of the target materials in air.In contrast, trivalent substitution gives the substitution:Ba2+ + Mn4+ ↔ Ln3+ + Mn3+; (Ln=La, Nd). This leads to a very limited susbtitution range, but additionally results in a loss of oxygen and hence a concomitant extra population of Mn3+ within the materials.Comparison of the specific composition Ba3.9A0.1Mn3O10with A = Sr, La or Nd has shown that, whilst Sr and La do not affect the magnetic properties, Ba3.9Nd0.1Mn3O10 is ferromagnetic below 100K. It would appear that the combination of the smaller cation size, together with trivalent charge, leads to reduced Mn-Mn distances, higher oxygen loss and hence a higher Mn3+ content in Ba3.9Nd0.1Mn3O10. The magnetic moment of Nd may also have an effect. The higher percentage of ferromagnetic Mn3+-O-Mn4+ interactions in this material thus leads to a change in the bulk magnetic properties.
12:00 PM - QQ7.9
New Low-Dimensional Iron(II) Phosphates Exhibiting Field-Dependent Magnetization Steps.
Shiou-Jyh Hwu 1 , Wendy Queen 1 , Lei Wang 1 , K. G. Sanjaya Ranmohotti 1
1 Chemistry, Clemson University, Clemson, South Carolina, United States
Show AbstractAchieving quantum-mechanical effects in solids that are made of extended three-dimensional structures is theoretically unattainable due to itinerate electrons. However, solids consisting of electronically confined low-dimensional magnetic nanostructures are thought to be capable of displaying magnetic quantum effects. Condensed matter systems containing geometrically frustrated magnetic (GFM) interactions, where the geometry of the spin lattice frustrates the spin-spin interactions, have been shown to display a wide range of novel ground states attributed to confined spins. One of which is exemplified by a quantum-tunneling-dominated magnetization relaxation process occurring in the so-called ''spin ice'' pyrochlore materials, such as Dy2Ti2O7 and Ho2Ti2O7, and Ca3Co2O6. We have recently discovered a new iron(II) phosphate 1, RbNa3Fe7(PO4)6, that exhibits magnetization steps in its hysteresis loop, possibly associated with the coupling of frustrated magnetic spins. 1 is a representative member of the ANa3M7(PO4)6 compound family, where A = K, Rb, Cs and M = Mn, Fe, Co. The extended structure comprises of alternating corner- and edge-sharing triangular chains of FeOn (n = 5,6) polyhedra involving four crystallographically distinct Fe(II) cations. The triangular chains propagate along the ab plane by P5+ cations into slabs that are interconnected by Fe(5)O4 to form the three-dimensional lattice. The fascinating compound series shows a ferromagnetic transition at temperatures around 15K. In this presentation, we will first discuss some background of prior research developments relevant to the study of GFM interactions. Followed by the results of our exploratory synthesis in the quaternary iron(II) phosphate system and initial investigations of temperature-, field- and frequency-dependent magnetic properties.
12:15 PM - QQ7.10
Materials Discovery by Crystal Growth.
Hans-Conrad zur Loye 1 , Samuel Mugavero 1 , William Gemmill 1 , Mark Smith 1
1 Chemistry & Biochemistry, University of South Carolina, Columbia, South Carolina, United States
Show AbstractQQ8: Synthesis and Structure
Session Chairs
Thursday PM, November 30, 2006
Grand Ballroom (Sheraton)
2:30 PM - **QQ8.1
Structure/Property Relationship of Water in Nanoporous Spaces: Characterization of Zeolites.
Tina Nenoff 1 , Nathan Ockwig 3 , Jacalyn Clawson 4 , Todd Alam 4 , Monika Hartl 2 , Luke Daemon 2
1 Surface & Interface Sciences, Sandia National Labs, Albuquerque, New Mexico, United States, 3 Geochemistry , Sandia National Labs, Albuquerque, New Mexico, United States, 4 Electronic & Nanostructured Materials, Sandia National Labs, Albuquerque, New Mexico, United States, 2 LANSCE-12, Los Alamos National Labs, Los Alamos, New Mexico, United States
Show AbstractZeolites and microporous materials are important materials for water purification. Sandia Octahedral Molecular Sieves (SOMS), Na2Nb1.6Ti0.4O5.6(OH)0.4-H2O, exhibits a high selectivity (10^5) for divalent cations, which is orders of magnitude better than the sieves end member Na2Nb2O6-H2O (10^3). Our research is focused on understanding the effect of the confined water on the ion selectivity in both SOMS frameworks and traditional aluminosilicate Zeolites, like Clinoptilolite ([Ca,Na,K,Li]4-6[Al6(Al,Si)4Si26O72]-24H2O). Characterization methods used in this study include inelastic neutron scattering (INS), MAS NMR, crystallographic structure refinement, and modeling/simulation. INS and NMR data indicate that the water in Na2Nb1.6Ti0.4O5.6(OH)0.4-H2O can be described as rotationally free, highly-mobile and bulk-like water species. However, in sharp contrast the occluded water in Na2Nb2O6-H2O behaves Ice-like and is one of the most rigid water environments investigated in inorganic materials to date. Preliminary DFT calculations of Na2Nb1.6Ti0.4O5.6(OH)0.4-H2O supports the INS and NMR data of rotationally free waters in energetically favorable locations near the framework atoms. The correlation between structure and property of the materials studied will be discussed. Sandia is a multiprogram laboratory operated by Sandia Corporation, Lockheed Martin Company, for US DOE’s NNSA, Contract DE-AC04-94-AL85000.
3:00 PM - **QQ8.2
Hydrogen Storage in Microporous Coordination Solids with Exposed Metal Sites.
Mircea Dinca 1 , Steven Kaye 1 , Anta Yu 1 , Jeffrey Long 1
1 Department of Chemistry, University of California, Berkeley, California, United States
Show AbstractMethods for synthesizing frameworks bearing coordinatively-unsaturated metal centers are being developed in order to increase the H2 binding enthalpy within microporous coordination solids. The porosity and hydrogen storage properties of the dehydrated Prussian blue analogues Ga[Co(CN)6], Fe4[Fe(CN)6]3, M3[Co(CN)6]2 (M = Mn, Fe, Co, Ni, Cu, Zn), M2[Fe(CN)6] (M = Mn, Co, Ni, Cu), and Co3[Co(CN)5]2 have been investigated. Means of incorporating metal carbonyl units within Zn4O(1,4-benzenedicarboxylate)3 have been devised, and attempts at decarbonylating the resulting materials will be described. In addition, the use of pyrazole- and tetrazole-based ligands for generating frameworks with open metal coordination sites will be discussed, with emphasis on a new sodalite-type framework exhibiting a high volumetric H2 storage capacity.
3:30 PM - QQ8.3
Double-substituted perovskites LaxSr1-xCo1-yMnyO3-δ for use in High-temperature Oxygen Separations: Synthesis, Characterization, and Permeation Properties.
Andrea Ambrosini 1 , Terry Garino 2 , Hongwu Xu 4 , Tina Nenoff 3
1 Chemical and Biological Systems, Sandia National Laboratories, Albuquerque, New Mexico, United States, 2 Electronic Materials & Nanostructured Materials , Sandia National Laboratories, Albuquerque, New Mexico, United States, 4 Los Alamos Neutron Science Center , Los Alamos National Laboratory, Los Alamos, New Mexico, United States, 3 Surface & Interface Sciences, Sandia National Laboratories, Albuquerque, New Mexico, United States
Show Abstract3:45 PM - QQ8.4
Topochemical Strategies for the Formation of Alkali-metal Halide Arrays within Perovskite Hosts.
Liliana Viciu 1 , Xiao Zhang 1 , Thomas Kodenkandath 1 , Vladimir Golub 1 , John Wiley 1
1 Department of Chemistry and the Advanced Materials Research Insititute, University of New Orleans, New Orleans, Louisiana, United States
Show Abstract4:00 PM - QQ8:SynStr
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4:30 PM - **QQ8.5
On the Fate of Crystalline Network Structures Upon Melting
James Martin 1
1 Department of Chemistry, North Carolina State University, Raleigh, North Carolina, United States
Show AbstractFundamental to understanding the properties of a material is an understanding of its structure at the level of chemical bonding. As such an understanding of crystalline structures has allowed solid state chemists to exploit numerous structure/property relationships. What, however, is the fate of chemical bonding when a network solid melts? And if structure persists into the melt, should it not also be possible to exploit structure/property relationships in the liquid state as well? Most crystalline solids exhibit a volume expansion of not more than 10-20% upon melting. If all this volume change upon melting were due to a change in atom-atom distances, one should not expect more than a 3-6% change in bond distances, i.e. on the order of thermal motion. Therefore, given that chemical bonding does not change drastically between the crystalline and liquid states, it should be possible to engineer structure and potentially specific properties in liquid materials. Using X-ray and neutron diffraction as well as solid state NMR spectroscopy we have been studying the comparative structure of crystalline and molten metal halides. A review of the periodic series of simple binary metal halides, CuCl, ZnCl2, AlCl3 and SiCl4 demonstrates the breakdown of a network into molecular units. Adding network modifiers further can be used to modify network structure. Specifically, the addition of monovalent salts (CsCl, H2NMe2Cl or NMe4Cl) to CuCl is used to demonstrate that it is the structural symmetry of the liquid, not the mobility of Cu+ (as previously thought) that governs the observed X-ray and neutron scattering patterns. Furthermore, 63Cu NMR spectroscopy suggests that while the copper is mobile in both solid and liquid phases it is not well described as a classical ionic conductor.
5:00 PM - QQ8.6
Probing Octahedral Tilting in Dion-Jacobson Layered Perovskites With Neutron Powder Diffraction and Raman Spectroscopy.
Margret Geselbracht 1 , Joshua Kurzman 1
1 Chemistry, Reed College, Portland, Oregon, United States
Show AbstractLayered perovskites provide a rich diversity of structures, compositions, chemical reactivity, and physical properties. Yet unlike the wealth of information that exists for three-dimensional perovskites, there is a paucity of detailed structural analyses of layered perovskites, particularly those containing early transition metals. Distortions and tilting in the octahedral framework characterize the single crystal X-ray structure of the Dion-Jacobson type phase CsCa2Nb3O10, however the structures of all other related phases have been modeled with no octahedral tilting. We will present neutron powder diffraction studies of RbCa2-xSrxM3O10 (M = Nb, Ta, x = 0, 1, and 2), triple layer Dion-Jacobson phases with different degrees of octahedral tilting in the perovskite slab. The refined structural models of the strontium phases, RbSr2Nb3O10 and RbSr2Ta3O10, exhibit a slight twist in the central octahedra of the perovskite slab. With a smaller cation on the A-site, the calcium analogs, RbCa2Nb3O10 and RbCa2Ta3O10, adopt lower symmetries dictated by more extensive octahedral tilting. Vibrational modes of the perovskite slab observed using Raman spectroscopy show subtle changes as a function of calcium/strontium content and more intriguing differences between the isostructural niobates and tantalates. A long-term goal of this work is to correlate the Raman spectral bands with the neutron structures so that Raman studies could be used to monitor structural changes in experimental settings that are not amenable to diffraction studies.
5:15 PM - QQ8.7
Structures, Chemistry and Electronic Properties of Layered Oxychalcogenides.
Simon Clarke 1 , Catherine Smura 1 , Geoffrey Hyett 1 , Oliver Rutt 1
1 Chemistry, University of Oxford, Oxford United Kingdom
Show AbstractLayered oxychalcogenides of the first row transition metals are underexplored compounds which show diverse electronic and magnetic properties. Of particular interest are compounds which are intergrowths of well-defined perovskite-type oxide slabs and anti-fluorite-type chalcogenide slabs. These compounds accept a wide range of iso- and aliovalent substitutions which can result in dramatic changes in physical properties. Here property tuning in two groups of layered oxychalcogenide will be discussed. 1. Members of the series A2CoO2Cu2Ch2 (A = Sr, Ba; Ch = S, Se) contain square planar CoO2 sheets and have conductivities which span several orders of magnitude and range in behaviour from insulating to metallic. The trends in structures and physical properties will be described as the insulator to metal transition is traversed with increasing x in the series Sr2CoO2Cu2(S1-xSex)2 and as the CoO2 layers become more isolated from one another with increasing x in the series (Sr1-xBax)2CoO2Cu2S2.2. Members of the series A4Mn3O7.5Cu2Ch2 (A = Sr, Ba; Ch = S, Se) contain much thicker perovskite slabs. These insulating materials exhibit partially frustrated antiferromagnetic ordering of Mn3+ moments below 100 K. A large concentration of anion vacancies exists in the oxide slabs of the structure. These vacancies may be filled by low temperature topotactic oxidative intercalation of fluorine, or further vacancies may be created by reductive low temperature topotactic deintercalation of oxygen. Oxidation and filling of vacancies eases the magnetic frustration while reduction completely destroys the long range antiferromagnetic ordering in these compounds. The scope for further developments in this area will be outlined.
5:30 PM - QQ8.8
NMR Studies of Oxysulfide Layered Materials.
Sylvio Indris 1 , Jordi Cabana 1 , Oliver Rutt 2 , Simon Clarke 2 , Clare Grey 1
1 Chemistry, SUNY Stony Brook, Stony Brook, New York, United States, 2 Inorganic Chemistry , Oxford University, Oxford United Kingdom
Show AbstractMaterials capable of inserting lithium are widely studied because of their potential use as electrode materials in high-voltage rechargeable batteries. Whereas the first cathode materials studied as intercalation hosts about three decades ago were layered dichalcogenides such as TiS2, with the development of the SONY cell in 1990, most current work has focuses on the development and study of oxide materials for positive electrode materials. A large variety of layered oxysulfides have now been prepared, which have not been studied intensively up till now as either positive or negative electrodes. The layered oxysulfides Sr2MnO2Cu2m-0.5Sm+1 (m = 1, 2, 3) consist of alternating Sr2MnO2 layers and copper sulfide layers. The copper sulfide layers resemble fragments of the Cu2S anti-fluorite structure and consist of single, double, or triple layers of CuS4 tetrahedra for m = 1, 2, 3, respectively. These materials can be chemically lithiated by using n-buthyl-lithium, the reduced copper being extruded from the structures to form fine copper metal particles. More recently, we have shown that reversible Li insertion may be achieved electrochemically; reversibility is improved over Cu2S, materials with thinner Cu2S slabs showing improved capacity retention. Li MAS NMR has been used to follow this process and investigate Li-ion mobility within the sulfide sheets.
5:45 PM - QQ8.9
Crystal Chemistry and Crystallography of a Novel Phase, Na1-xGe3+z.
Winnie Wong-Ng 1 , Matthew Beekman 2 , George Nolas 2 , James Kaduk 3 , Qing Huang 4 , Zhi Yang 1
1 Ceramics, NIST, Gaithersburg, Maryland, United States, 2 Physics Department, University of South Florida, Tampa , Florida, United States, 3 , INEOS Technologies, Naperville, Illinois, United States, 4 Center for Neutron Research, NIST, Gaithersburg, Maryland, United States
Show AbstractQQ9: Poster Session III
Session Chairs
Friday AM, December 01, 2006
Exhibition Hall D (Hynes)
9:00 PM - QQ9.10
BaCe1-xPdxO3±δ (0≤x≤0.1): Redox Controlled Ingress and Egress of Palladium in a Perovskite.
Jun Li 1 , Udayshankar Singh 2 , Katharine Page 1 , James Weaver 3 , Jinping Zhang 1 , Thomas Proffen 4 , Susannah Scott 2 , Ram Seshadri 1
1 Materials Research Laboratory, University of California, Santa Barbara, Santa Barbara, California, United States, 2 Department of Chemical Engineering, Department of Chemistry and Biochemistry, University of California, Santa Barbara, Santa Barbara, California, United States, 3 Department of Molecular, Cellular and Developmental Biology, University of California, Santa Barbara, Santa Barbara, California, United States, 4 Manuel Lujan Jr. Neutron Scattering Center, Los Alamos National Laboratory, Los Alamos, New Mexico, United States
Show AbstractWe demonstrate using a combination of X-ray and neutron diffraction, and X-ray photoelectron spectroscopy that Pd2+ ions can be incorporated at the Ce site in perovskite BaCeO3, and that under oxidizing conditions, BaCe1-xPdxO3±δ (0≤x≤0.1) compositions can be prepared. These Pd2+ containing species release elemental fcc-palladium when heated in a reducing atmosphere. The elemental palladium is reabsorbed as ions into the perovskite lattice upon heating in flowing oxygen. Evidence for such cyclable ingress and egress of palladium under redox conditions is presented, and implications for heterogeneous catalysis by noble metal particles supported on oxide hosts are pointed out. A curious morphological change that results from the redox cycling of BaCe1-xPdxO3±δ (0≤x≤0.1) is the formation of nanowires, which we believe to arise from regrowth of the perovskite around elemental palladium particles. The implications of the formations of these nanostructures are examined.
9:00 PM - QQ9.11
Microwave Conductivities of Alkali-metal Loaded Zeolites.
Asako Watanabe 1 , Nobuya Hiroshiba 1 , Ryotaro Kumashiro 1 2 , Katsumi Tanigaki 1 2 , Mayumi Mori 1 , Hiroshi Matsui 1 , Naoki Toyota 1
1 Physics, Tohoku University, Sendai, Miyagi, Japan, 2 , CREST, Kawaguchi, Saitama, Japan
Show Abstract9:00 PM - QQ9.12
Physical Properties of Oxygen Composition Controlled La1-xSrxMnOy Single Crystals.
Yuui Yokota 1 , Jun-ichi Shimoyama 1 , Tetsuro Ogata 1 , Shigeru Horii 1 , Kohji Kishio 1
1 Department of Applied Chemistry, University of Tokyo, Tokyo Japan
Show AbstractThe perovskite manganese oxides La1-xSrxMnOy [(La,Sr)Mn113] has been investigated for development of functional materials, such as electrodes for SOFC and magnetoresistance heads thus far. (La,Sr)Mn113 shows various magnetic and crystal structures with strontium substitution and excess oxygen levels. Although the excess oxygen corresponds to the generation of cation vacancy and directly affects the valence of manganese ions, effects of excess oxygen on the physical properties have not been well understood compared to the effects of strontium composition because of difficulty in precise control of excess oxygen in bulky single crystals. In the present study, excess oxygen of (La,Sr)Mn113 single crystals with various strontium substitution levels were systematically controlled and its intrinsic effects on the electronic and magnetic properties and crystal structure were studied.Single crystals with nominal compositions of La1-xSrxMnOy (0 ≤ x ≤ 0.175) were grown by the floating zone method. Small rectangular crystals with wide ab-plane or ac-plane were cut from the grown crystal boules by means of X-ray Laue method. Thicknesses of the samples were decreased down to ∼100 μm in order to achieve homogeneous introduction of excess oxygen by post-annealing at various temperatures in air or O2.The as-grown crystal of La0.95Sr0.05MnOy (x = 0.05) indicated an antiferromagnetic transition at ∼130 K on magnetization measurement, however, the ferromagnetic behaviors appeared by introduction of excess oxygen. The TC systematically increased with increasing excess oxygen content. These results are attributable to an increase of mean valence of manganese ions by introduction of excess oxygen. In addition, magnetization under H // c was larger than that under H // ab for as-grown crystals below TC, whereas both magnetization under H // c and that under H // ab approached almost similar behavior that is considered to be due to the change of crystal structure from rhombohedral to orthorhombic. Behaviors of magnetization and electrical resistivity under several magnetic fields as functions of strontium substitution and excess oxygen levels of (La,Sr)Mn113 and will be reported.
9:00 PM - QQ9.13
Hydrothermal Synthesis and Growth Morphology of Ruby Crystals.
Buguo Wang 1 , David Bliss 2 , Kelly Rakes 2 , Michael Callahan 2
1 , Solid State Scientific Corporation, Nashua, New Hampshire, United States, 2 , Air Force Research Laboratory, Hanscom AFB, Massachusetts, United States
Show AbstractHydrothermal synthesis and growth is a technique that has several advantages over traditional melt growth for ruby (chromium doped α-Al2O3) crystals. Ruby is of commercial interest for its application as a high power laser host material that is usually produced by melt growth. However, because of the impurity segregation effect, it is not possible to grow homogeneous crystals from the melt with uniform chromium concentration. Hydrothermal growth can be used to produce high quality ruby crystals of large size and uniform doping concentration. Although there are some reports on hydrothermal synthesis of ruby material, the growth of single crystal ruby under hydrothermal conditions, and particularly the growth morphology in relation to its structure, is rarely discussed in the literature. Here we report the hydrothermal synthesis of ruby crystals using white sapphire (α-Al2O3) from the edge-defined film-fed growth (EFG) and commercial Cr2O3 as nutrients, EFG α-Al2O3 as seeds and potassium carbonate as mineralizer. The experiments were performed at 475-550°C and 15-25 kpsi. The ruby crystals obtained have well-defined morphology and were characterized by X-ray diffractions, optical microscopy and elemental analysis. The growth characteristics of ruby, particularly the growth morphology in relation its structure and growth conditions will be discussed.
9:00 PM - QQ9.14
Cd1-xMnxBiSe2I (0 < x < 0.3) : A New Series of Mn-Doped Ferromagnetic Semiconductors
Lei Wang 1 , Shiou-Jyh Hwu 1
1 Department of Chemistry, Clemson University, Clemson, South Carolina, United States
Show AbstractThe next generation information technology requires greater complexity, multiple functionality and multiple compositions of materials. Spintronic devices, for instance, utilize materials with combined magnetism (spin) and semiconductivity (charge) that exploit both charge and magnetic spin to process and to store information. Magnetic ions can be introduced into a non-magnetic semiconductor host to give rise to desired ferromagnetic properties in so-called diluted magnetic semiconductors (DMSs). II-VI, III-V semiconductors, for example, have been employed as host materials. Due to the lack of preferred cation substitution, cluster formation of magnetic ions has hampered the materials development. Our solution is to synthesize solids that have specific crystallographic sites suitable for controlled magnetic ion substitution. Our approach in solid-state synthesis is to explore host semiconducting solids that possess mixed-framework structures consisting of cations having unique coordination geometry commonly adopted by magnetic ions. We report here the results of magnetic doping in one of the new ternary chalcohalide semiconductors, CdBiSe2I, discovered in our laboratory (Chem. Mater. 2006, 18, 1219-1225). This selenoiodide was systematically doped with a small increment of Mn2+ ions, and the resulting solids exhibit a gradual variation of ferromagnetism at the temperatures between 40 and 50 K. We will discuss the synthesis of the solid solution series Cd1-xMnxBiSe2I (0 < x < 0.3) that has been prepared in both polycrystalline and single crystal forms. The structure of CdBiSe2I consists of alternating CdSe6 and CdSe2I4 octahedra which form slabs that adopt the (110) plane of a distorted NaCl-type structure. The isoelectronic cation substitution of Mn2+ for Cd2+ was found exclusively at the CdSe2I4 sites via X-ray single crystal structure analysis. The temperature-dependent magnetic susceptibility measurements show that, at temperatures below 40 K, selected samples with a nominal Mn2+ composition (x = 0.025, 0.05, 0.075, 0.10 and 0.20) show an antiferro- (AFM) to ferromagnetic (FM) transition. More detailed magnetic investigations, including zero-field cooling (ZFC) and field cooling (FC), show consistent results. At 5, 35, and 45 K, the magnetic hysteresis study on the x = 0.10 sample reveals that the coercive field decreases from 2100 Oe to 163 Oe, which confirms the ferromagnetic coupling. In this presentation, we will discuss the results of exploratory synthesis, crystal growth, structure analysis, and magnetic property investigations. We will also comment on the correlation between the magnetic behavior and the crystal structure with respect to the reduction of magnetic clustering due to preferential cation substitution.
9:00 PM - QQ9.15
Computer Modeling of Nanoporous Materials: An ab initio Novel Approach for Silicon and Carbon.
Ariel Valladares 1 , Alexander Valladares 2 , R. Valladares 2
1 Condensed Matter, IIM-UNAM, Mexico, D.F. 04510 Mexico, 2 Physics, Facultad de Ciencias-UNAM, Mexico, D.F. 04510 Mexico
Show AbstractPorous semiconductors are in the forefront of potentially useful materials. It is well known that porous silicon is photoluminescent and that laboratory prototypes are being developed for diverse applications. Carbon and silicon, being group IV materials, are similar, yet very different due to the types of bonding they display. Whereas silicon is essentially tetrahedrally bonded, carbon displays a rich variety of bonds that make it very versatile; these bonds lead to different types of molecules or solids not encountered in other elements belonging to group IV of the Periodic Table. Therefore, nanoporous carbon should manifest some of this richness in structure and properties compared to nanoporous silicon. This is why their study is a challenging and interesting subject. However one has to begin by obtaining representative structures and an adequate topology of these materials in the nanoregime. Previous work [1] for amorphous porous silicon indicates that the computer modeling techniques developed by our group [2] for semiconducting random networks lead to reasonable results. We have now devised a novel approach that generates more realistic pore structures, since the pores are generated without a predetermined orientation and therefore may better represent porous materials. The method consists of choosing a periodic supercell with 216 atoms (silicon or carbon) and a volume adequate to the porosity we want to emulate (50 % in this work), and subjecting it to a 300 K ab initio molecular dynamics simulation. Once the structures are formed we relax them, look at the pore structure and its orientation, and determine the pair distribution functions to analyze its amorphicity. We shall draw a comparison between materials and discuss the potentiality of our approach.1. E.R.L. Loustau, R. M. Valladares and A. A. Valladares, J. Non-Cryst. Solids 338-340 416 (2004).2. F. Alvarez and A. A. Valladares, Phys. Rev. B 68 205203_1 (2003), and references contained therein.
9:00 PM - QQ9.16
High-pressure Synthesis, Crystal Structure, and Physical Properties of a Novel PbFeO3.
Takeshi Tsuchiya 1 , Tetsuhiro Katsumata 1 , Yoshiyuki Inaguma 1
1 Chemistry, Gakushuin University, Tokyo Japan
Show Abstract9:00 PM - QQ9.17
Physical Properties of Type I Clathlates as Thermoelectric Material.
Takuya Nishino 1 , Nobuya Hiroshiba 1 , Takeshi Rachi 1 , Naoki Miyata 1 , Haruki Eguchi 2 , Ryotaro Kumashiro 1 3 , Katsumi Tanigaki 1 3
1 , tohoku univercity, Sendai Japan, 2 , Ishikawajima-HarimaHeavy Industries Co., Ltd., kanagawa Japan, 3 , CREST, Kawaguti Japan
Show AbstractClathrates whose frame made of Si and Ge are known to be semiconducting. Their compounds consist of face-shared polyhedral cages(formed by Si,Ge,Sn, and/or Ga) filled with alkali-metal,alkaline-earth and/or rare-earth atoms. The most pronounced feature of clathrate compounds is their very low lattice thermal conductivity. This compounds even show glasslike temperature-dependent thermal conductivity, although they crystallize in well-defined structures. These classes of compound are good candidates to fulfill the phonon glass electron crystals concept, which is a guideline to search for high performance thermoelectric materials with the compatibility of low thermal conductivity and high electriclad conductivity. The thermoelectric performance of a material at a given operation temperature T is characterized by the dimensionless figure of merit ZT, which is defined as(ZT=S2(σ/κ)T), where S, κ and σ, are the thermoelectric power, sum of lattice and electronic thermal conductivity , and electric conductivity respectively. We report on investigations of type I clathlate. In particular, we have been interested in Si and Ge. Because this type is very different from the conventional diamond structure, consists of cluster polyhedra of (Si,Ge)20,(Si,Ge)24 and (Si,Ge)28 as a unit of the crystals and the characteristics of these cluster crystals are covalent, and their structre can precisely be controlled in a nano scale size. So the related reseaches have resulted in a surge of interest as nano materials to date. Heterogeneous clathrates consisting of III-group elements are reported to be formulated and much attention has been paid to these materials for the purpose of introducing carriers through direct network-substitutions AE8III16(Si,Ge)30(AE=Ba,Sr,III=Al,Ga,In) with the type I structure are being extensively studied as thermo-electric power materials with a great figure of merit in high temperature region. It should be very interesting to study the transport proterties of AE8III16(Si,Ge)30 in order to understand the reason of this interesting propertyIn this meeting, we will present comparison of the various properties, such as seebeck coefficient, electronic and thermal conductivitiy, of AE8III16(Si,Ge)30, and discuss the effect of direct network-substitutions to thermo-electric property.From the experimental results, it will be demonstrated that the value of ZT factor can be changed with both kinds of the network and encapsulated atoms and Ba8Ga16Ge30 particularly shows high ZT factor value near the practical material. We will also discuss the relationship between the electronic state and thermo-electric property of clathrates.
9:00 PM - QQ9.18
Aqueous Synthesis of Vanadium Oxide Nanoparticles Under Ambient Conditions.
William Morris 1 , C. Lukehart 1
1 Department of Chemistry, Vanderbilt University, Nashville, Tennessee, United States
Show AbstractA method for the preparation of vanadium oxide nanoparticles, with a variety of elemental compositions, is reported here. This method employs sol-gel chemistry and a subsequent thermal treatment to yield spherical and rod-shaped crystalline particles within the nanometer and sub-micrometer size regime. The growth of vanadium oxide particles with water as the singular solvent affords a low-cost and environmentally friendly synthetic method to yield a free-flowing powder that can be dispersed into a range of solvents, polymers, or onto solid supports for various applications. TEM, SEM, XRD, and EDS were used to characterize the structure, size, and composition of the resulting vanadium oxide.
9:00 PM - QQ9.19
The Synthesis and Characterization of CsAeBiO2Cl2 (Ae = Ca, Sr, Ba).
Elisha Josepha 1 , Tapas Mandal 1 , John Wiley 1
1 Chemistry Department, University of New Orleans, New Orleans, Louisiana, United States
Show AbstractA new series of Sillèn-related bismuth oxyhalides has been prepared. The general formula of the parent compounds is AeBiO2X (Ae = Ca, Sr, Ba) and the their structure can be described as metal-oxygen blocks (AeBiO2) that are separated by halide layers. The parents are reacted with CsCl and the products appear to have a similar layered bismuth oxyhalide structure. Details on the synthesis and characterization of CsAeBiO2Cl2 (Ae = Ca, Sr, Ba) will be presented and the ability to manipulate these Sillèn-related bismuth oxyhalide compounds topochemically will be discussed.
9:00 PM - QQ9.2
Preparation of Hierarchically Structured SnO Crystal by Dissolution-reprecipitation from Sn6O4(OH)4 by Hydrothermal Process.
Hiroaki Uchiyama 1 , Hiroaki Imai 1
1 , Keio University, Yokohama Japan
Show Abstract9:00 PM - QQ9.21
Absence of Ferromagnetism in Conductive Nb: SrTiO3 with Magnetic Transition Element (Cr, Co, Fe, Mn) Dopants.
Shixiong Zhang 1 , Satish Ogale 1 3 , Darshan Kundaliya 1 , Lianfeng Fu 2 , Nigel Browning 2 , Sanka Dhar 1 , Wegdan Ramadan 1 , Joshua Higgins 1 , Richard Greene 1 , Thirumalai Venkatesan 1
1 Center for Superconductivity Research, Department of Physics, University of Maryland, College Park, Maryland, United States, 3 , National Chemical Laboratory, Pune India, 2 Department of Chemical Engineering and Materials Science, University of California at Davis, Davis, California, United States
Show Abstract9:00 PM - QQ9.22
Structural and Magnetic Properties of the Sr2-xLaxIrO4 System.
Carlos Cosio-Castaneda 1 , Gustavo Tavizon 1 , Pablo de la Mora 1 , Roberto Escudero 1
1 , National Autonomous University of Mexico, Mexico, Mexico City, Mexico
Show Abstract9:00 PM - QQ9.23
Soft X-ray Studies of Ba8Ga16IV30 (IV=Si and Ge) and Sr8Ga16Ge30 Thermoelectric Materials
Kiyotsugu Narita 1 , Takeshi Rachi 1 , Ryotaro Kumashiro 1 2 , FangZhun Guo 3 , Keisuke Kobayashi 3 , Marcoss Avila 4 , Toshiro Takabatake 4 , Katsumi Tanigaki 1 2
1 Physics, Tohoku University, Sendai Japan, 2 , JST-CREST, Kawaguchi Japan, 3 , JASRI/SPring-8, Sayo-chou Japan, 4 Advanced sciences of matter, Hiroshima University, Hiroshima Japan
Show Abstract Thermoelectric materials have been gathering lots of attention for achieving high efficiency in energy conversion from heat to electricity, and this is believed to resolve the serious energy problems in the future. As for the methodologies for realizing good thermoelectric power materials, the following guiding principles can be considered. The first category of such a guideline is using the highly electron-correlated system. Perovskite type Co oxides recently found to show a high figure of merit parameter as thermoelectric power materials will be such a good example. The second category is to use the B and Al based quasi-crystals. Due to the pseudo energy gap arising at the Fermi level, this family of materials also show a high figure of merit, and this is thought to be due to the increased effective mass. Another one is the category of materials where magnetic spin systems are included. However, this guiding principle has not resulted in any good thermoelectric materials so far. The other category is to apply clathrates having nano cage structure. In clathrates, the important factor is the phonons arising from the atomic elements endohedrally confined inside the cage. Because of the spaces inside the cages, the atomic phonons will be very much different from the conventional lattice phonons. These endohedral atomic phonons will have time- and space-dependent anharmonic characteristics and are called as rattling phonons, being collecting much attention among the community of thermoelectric materials. We have successfully prepared three single crystal clathrates of Ba8Ga16Si30 , Ba8Ga16Ge30 and Sr8Ga16Ge30 , all of which show good efficiency as thermoelectric materials. Therefore, it is of great importance to study electronic states of these clathrates. We have applied soft X ray photoelectron spectroscopy to study the band structure at the Fermi level and valence states of these clathrates as a function of temperature. In addition, core-level states of the compositional elements of Ba, Sr, Ga, Si and Ge have been studied in detail. In this meeting, we will discuss the efficiency of thermoelectric power figure of merits using electric conductivity, thermal conductivity and Seebeck coefficient as well as energy band obtained in the present study.
9:00 PM - QQ9.24
Designing Semiconductor Nanocomposites for Thermoelectric Applications
Jeff Urban 1 , Christopher Murray 1 , Mercouri Kanatzidis 1
1 , IBM/MSU, Yorktown Heights, New York, United States
Show AbstractIn this presentation, recent work on the development of binary nanocomposites for thermoelectric applications will be discussed. It will cover our progress along the entire developmental chain, from nanomaterials discovery to thin-film assembly and characterization to electronic and thermal measurements. Specifically, the development of two nanoparticle materials systems (PbTe and Ag2Te) targeted for the p-type leg of a thermoelectric device will be discussed, along with the full structural, optical, and electronic characterization of each individual component. Furthermore, the assembly of these two nanocrystalline systems into binary nanoparticle superlattices is demonstrated. This design motif enables the introduction of dopants into our nanoparticle composites, a concept supported by measurements on the mixed PbTe/Ag2Te thin films. A recent exploration into the thermal diffusivity of thin films and potential methods to access complementary n-type nanoparticle composite thermoelectrics will also be highlighted.
9:00 PM - QQ9.25
Characterization of Bi5Nb3O15 by Refinement of Neutron Diffraction Pattern and Acid Treatment
Seiichi Tahara 1 , Akira Shimada 1 , Nobuhiro Kumada 2 , Yoshiyuki Sugahara 1
1 Department of Applied Chemistry, Waseda University, Tokyo Japan, 2 , Yamanashi University, Yamanashi Japan
Show AbstractBi5Nb3O15 was characterized by refinement of powder neutron diffraction pattern and acid treatment. Bi5Nb3O15 was prepared by calcination of the mixture of Bi2O3 and Nb2O5 (the molar ratio of 5:3). The structural refinement of neutron diffraction pattern using the Rietveld method with the program RIETAN2000 indicated that Bi5Nb3O15 was an intergrowth Aurivillius-related phase (Pnc2 (space group No. 30), a = 2.0990(1), b = 0.5463(3), c= 0.5451(3) nm). After the acid treatment of Bi5Nb3O15 with 3 M HCl, new low-angle reflections (at 2.21 nm after drying at room temperature and 1.88 nm after drying at 120 degree-C) appeared in X-ray diffraction patterns in addition to the reflections due to Bi5Nb3O15. Inductively coupled plasma emission spectrometry of acid-treated product demonstrated that a part of Bi3+ ion was lost. The reaction of acid treated product after drying at room temperature with n-alkylamines led to the shifts of the newly-appeared reflection to lower angle. These results indicate that the Bi2O2 sheet in Bi5Nb3O15 was partially leached by acid treatment to form a layered structure that can accommodate n-alkylamines in the interlayer space, being consistent with the structural refinement.
9:00 PM - QQ9.26
Hydrothermal Synthesis and Characterisation of Novel Fluoroborates.
Thushitha Mahenthirarajah 1
1 Chemistry, University of St-Andrews, Fife United Kingdom
Show AbstractResearch into metal borates has steadily increased during the past decade in the field of various non-linear optical (NLO) devices, as they are capable of expanding the frequency range provided by common laser sources. Our current program is aimed at the exploration and development of novel synthetic methods towards mixed metal borates incorporating fluoride ion.Mixed metal borates in the systems A-M-(BO3)-F where A and M are alkali, alkaline earth metals, d0 or d10 transition metals have been prepared and characterised. The aim is to produce non-centrosymmetric crystals which can be used in NLO application. Several new borate materials have been synthesised and their NLO properties will be discussed in relation to their crystal structures
9:00 PM - QQ9.27
Hydrothermal Ion-exchange on Submillimeter-Size Single Crystals of New Iron(III) Phosphates.
Shiou-Jyh Hwu 1 , Greg Becht 1
1 Chemistry, Clemson University, Clemson, South Carolina, United States
Show AbstractExtended solids that reveal ion-transport properties are attractive for their potential applications in fuel cell and battery devices. To investigate chemical transport properties, one would preferentially employ polycrystalline samples in order to expedite the diffusion process across the interface. While a small-size particle conceivably offers increased surface area in favor of ion-transport, it presents fundamental challenges in structure characterization. Often there is a prolonged delay in materials development due to the lack of immediate access to specialized instrumentation, such as solid state NMR and neutron diffraction, required to reveal the ion distribution in resulting solids. To acquire a timely evaluation on chemical transport properties of our newly synthesized materials, we have proceeded with a direct ion-exchange on single crystals followed by conventional single crystal X-ray diffraction methods. The parent compounds used in this study were new iron(III) phosphates, (Cs,K)9Fe7(PO4)10 and (Cs,K)3Fe3(PO4)4. To the best of our knowledge, this is the first time direct ion-exchange on single crystals while employing mild hydrothermal conditions has been reported. We have used temperatures as low as 120-200oC rather than using molten salt at higher temperatures. This approach arose due to the recognition of the sizable channel structures created by electropositive ions larger than Li+. As anticipated, ion-exchange does occur readily and the product preserves the crystal morphology, as shown by scanning electron microscopy. The (Cs,K)3Fe3(PO4)4 series also displays reduction chemistry via the insertion of additional Li+ ions. In this presentation we will first discuss some background of prior research developments relevant to the study of polyanion-based transition metal oxide materials for battery applications, followed by the results of our exploratory synthesis in the iron(III) phosphate systems and initial studies of ion-exchange reactions.
9:00 PM - QQ9.28
New Low-dimensional Oxohalide Compounds – Some Structural Features.
Richard Becker 1 , Mats Johnsson 1 , Helmuth Berger 2
1 Inorganic Chemsitry, FOS-chemistry, Stockholm Sweden, 2 , Institut de Physique de la Matiere Complexe, Lasuanne Switzerland
Show AbstractA synthesis concept that has proved applicable for finding new low-dimensional compounds uses p-element cations with stereochemically active lone pairs and halides as “chemical scissors” to reduce the three dimensional arrangement of e.g. transition metal cations in a crystal structure. During the last years several new low-dimensional oxohalide compounds with intriguing crystal structures have been synthesised utilizing this synthesis concept [1-2]. In this study a comparison is made in between the two lone pair cations Te4+ and Se4+. Both these ions most often have clearly stereochemically active lone-pairs and are relatively strong Lewis acids so they therefore tend to bond only to oxygen in an oxohalide. On the other hand the late transition metal cations that are weaker Lewis acids bond to both oxygen and halide ions. The difference in ionic radius for Te4+ and Se4+ is about 30 % and typically the larger Te4+ (ri = 0.66 Å) ion accepts a one sided coordination with three or four oxygen ligands so that when the stereochemically active lone-pair, E, is included a tetrahedral [TeO3E] or a trigonal bipyramidal [TeO3+1E] coordination with one longer Te-O bond is formed. Se4+ (ri = 0.50 Å) on the other hand only takes the tetrahedral [SeO3E] coordination. It can then be assumed that for compounds where Te4+ only accepts the [TeO3E] coordination, there will also exist an iso-structural Se4+ analogue. This statement is supported by experiments; The compound Cu3(TeO3)2Br2 has a tetrahedral [TeO3E] coordination and the next oxygen is around 3.9 Å away and also the iso-structural analogue β-Cu3(SeO3)2Cl2 has been found. The compound Co5(TeO3)4Br2 has a fourth Te-O distance that is much shorter (~2.7 Å) and the Se-analogue Co5(SeO3)4Br2 has a different crystal structure.
Oxohalides containing Cl– (ri = 1.81 Å) or Br– (ri = 1.96 Å) have been synthesised, and most often these analogues are iso-structural due to the small difference in ionic radius (~10%) in between the halide ions e.g. Co5(TeO3)4X2 (X = Cl, Br). However, sometimes the size difference is sufficient so that the Cl- and the Br-analogues are not isostructural e.g. Co2TeO3Cl2 and Co2TeO3Br2.
We acknowledge the support from the Swedish Research Council, the Swiss National Science Foundation (SNSF) and Materials with Novel Electronic Properties (MaNEP).
[1] M. Johnsson, K. W. Törnroos, F. Mila, and P. Millet: “Tetrahedral Clusters of Copper (II): Crystal Structures and Magnetic Properties of Cu2Te2O5X2 (X = Cl, Br)”, Chem. Mater. 12 (2000) pp. 2853-2857.
[2] M. Johnsson, S. Lidin, K. W. Törnroos, H. -B. Bürgi and P. Millet: “Novel host-guest compounds in the family of tellurium-nickel oxohalogenides”, Angewandte Chemie. Int. Ed., 43 (2004) pp. 4292-4295.
9:00 PM - QQ9.3
Application of Resonant X-ray Diffraction for Investigation of Crystal Structures of Novel Sulfide Photocatalysts.
Valery Petrykin 1 , Yoshiki Shimodaira 2 , Issei Tsuji 2 , Akihiko Kudo 2 3 , Hisayoshi Kobayashi 4 , Satoshi Sasaki 5 , Masato Kakihana 1
1 Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai, Miyagi, Japan, 2 Department of Applied Chemistry, Tokyo University of Science, Tokyo, Tokyo, Japan, 3 Core Research for Evolutional Science and Technology, Japan Science and Technology Agency, Kawaguchi-shi, Saitama, Japan, 4 Department of Chemistry and Materials Technology, Kyoto Institute of Technology, Kyoto, Osaka-fu, Japan, 5 Materials and Structures Laboratory, Tokyo Institute of Technology, Yokohama, Kanagawa, Japan
Show Abstract9:00 PM - QQ9.31
Electrospinning of Single-Crystalline Vanadium Oxide Nanorods.
Chunmei Ban 1 , M.Stanley Whittingham 1
1 Chemistry, SUNY at Binghamton, Binghamton, New York, United States
Show AbstractVanadium oxide nanorods intercalated with lithium cations have been successfully formed by hydrothermal treatment of electrospun precursors. The novelty of this synthesis method is to control the morphology of vanadium compound nanorods by electrospinning process, and form compounds with desirable layered structure through hydrothermal treatment. Transmission Electron Microcopy images show that the single nanorods formed have square shape cross-section with a width of less than 100nm. Electron diffraction shows that each nanorod is a single crystal, and their structure is related to the delta V4O10 structure with a 10.5 Å layer spacing. Their characterization, magnetic and electrochemical behavior and variable chemical composition will be described together with the opportunities electrospinning presents for forming novel materials. This work was supported by NSF-DMR.
9:00 PM - QQ9.4
Synthesis of Monodisperse Silver Nanocubes.
Joseph McLellan 1 , Benjamin Wiley 1 , Andrew Siekkinen 1 , Younan Xia 1
1 Chemistry, University of Washington, Seattle, Washington, United States
Show Abstract9:00 PM - QQ9.5
Amplified Photochemistry with Slow Photons.
Jennifer Chen 1 , Georg von Freymann 1 2 , Sung Yeun Choi 1 , Vladimir Kitaev 1 3 , Geoffrey Ozin 1
1 Chemistry, University of Toronto, Toronto, Ontario, Canada, 2 Institut für Nanotechnologie, Forschungszentrum Karlsruhe in der Helmholtz-Gemeinschaft, Karlsruhe Germany, 3 Chemistry, Wilfrid Laurier University, Waterloo, Ontario, Canada
Show AbstractNanocrystalline TiO2 (nc-TiO2) in the anatase phase is widely used for photodegrading organic pollutants in a variety of environmental applications. Herein we show that slow photons in photonic crystals fashioned from nc-TiO2 can optically amplify the photocatalytic efficiency as a result of the longer path length of light and increased probability in anatase absorption. We investigated the photodegradation of adsorbed methylene blue on inverse TiO2 opals (i-nc-TiO2-o) with different stop-band energies under monochromatic and white light irradiation. By using template spheres with different diameters the energy of the slow photons was tuned in-and-out of the anatase electronic absorption, thereby allowing the systematic study of the effects of photonic structure on the photodegradation efficiency of TiO2. We first examined the kinetics of methylene blue decomposition under monochromatic irradiation at 370±10 nm. A remarkable twofold enhancement was observed for i-nc-TiO2-o with stop band at 345 nm as a result of slow photon coupling at 370 nm, the red-edge of the stop band. On the other hand, when the energy of the photonic stop band coincided with that of the irradiating light, as the case for i-nc-TiO2-o with stop band at 370 nm, partial light reflection lead to a lower photocatalytic efficiency as compared to nc-TiO2. For i-nc-TiO2-o without any photonic effects near 370 nm, the photocatalytic efficiency was found to be comparable to nc-TiO2. The practicality of slow photons in realistic photodegradation condition, namely under white light (>300 nm), was then investigated. An increase in the photodegradation efficiency was observed when the stop band moves from 370 to 300 nm, as a result of slow photon coupling and the suppression of stop-band reflection by the anatase absorption. By optimizing the energy of the photonic stop band with respect to the semiconductor electronic bandgap, we effectively harvested slow photons in the dielectric part of the material to give optically amplified photochemistry.
9:00 PM - QQ9.6
Study of Magnetism of Face-Center-Cubic Double Perovskite Compounds.
Tomoko Aharen 1 , John Greedan 1 , Takashi Imai 2 , Graeme Luke 2
1 Department of Chemistry, McMaster University, Hamilton, Ontario, Canada, 2 Department of Physics, McMaster University, Hamilton, Ontario, Canada
Show AbstractGeometric magnetic frustration usually occurs where the magnetic sub-lattice is based on triangles or tetrahedra. The B site ordered double perovskite compound, A2BB’O6 is a good candidate for this study because this compound can accommodate various combinations of cations (A, B, B’). More importantly, the magnetic ion (B’) topology is face-center-cubic which shows geometric magnetic frustration based on edge-sharing tetrahedra. The structure of this compound allows for the preparation of materials with different magnetic ions (varying spin quantum number), with nearly the same crystal structure.In this presentation, I will present the study of the magnetic properties of La2LiMO6 (M= Ru, Re, Mo) and Ba2YMO6 (M=Ru, Re, Mo) double perovskite compounds which show some trends in terms of spin quantum number, S. For example, La2LiRuO6, Ru5+, S=3/2, shows long range antiferromagnetic ordering, while, La2LiMoO6, Mo5+, S=1/2, doesn’t. This may be due to quantum fluctuations. Results of magnetization, heat capacity, NMR and muSR studies will be presented.
9:00 PM - QQ9.7
Structural Characterization, Magnetic Behaviour and High-Resolution EELS Study of New Perovskites Sr2Ru2-xCoxO6 (0.5≤x≤1.5).
Antonio Lozano-Gorrin 1 2 , John Greedan 1 2 , Gianluigi Botton 2 , Guillaume Radtke 2 , Cristina Gonzalez-Silgo 3 , Pedro Núñez 4
1 Chemistry, McMaster University, Hamilton, Ontario, Canada, 2 , Brockhouse Institute of Materials Research, Hamilton, Ontario, Canada, 3 Fisica Fundamental, Universidad La Laguna, La Laguna, Tenerife, Spain, 4 Quimica Inorganica, Universidad La Laguna, La Laguna, Tenerife, Spain
Show Abstract9:00 PM - QQ9.8
Fluoride Doping and Relaxor Behaviour in the Ferrolectric Two Layer Aurivillius Ccompounds ABi2Nb2O9.
Richard Goff 1 , Philip Lightfoot 1 , David Walker 2 , Dean Keeble 2 , Pam Thomas 2
1 Chemistry, St Andrews University, St Andrews United Kingdom, 2 Physics, Warwick University, Coventry United Kingdom
Show Abstract9:00 PM - QQ9.9
Beating the Heat: A Low Temperature Route to Negative Thermal Expansion Materials in the A2M3O12 Family.
Cora Lind 1 , Stacy Gates 1
1 Chemistry, University of Toledo, Toledo, Ohio, United States
Show Abstract