T. John Balk University of Kentucky
Andrew Minor Lawrence Berkeley National Laboratory
Alexandra Porter Cambridge University
Juergen Plitzko Max-Planck-Institute of Biochemistry
KK1: Advanced Electron Microscopy Techniques for Hard Materials
Monday AM, November 27, 2006
Fairfax A (Sheraton)
9:30 AM - **KK1.1
3D Imaging of Hard and Soft materials through Aberration-Corrected Scanning Transmission Electron Microscopy.
Stephen Pennycook 1 , A. Borisevich 1 , K. van Benthem 1 , A. Lupini 1 , N. de Jonge 1 , Y. Peng 1 , M. Oxley 1 Show Abstract
1 , Oak Ridge national Laboratory, Oak Ridge, Tennessee, United States
For the last 70 years the key motivation for the correction of lens aberrations in electron microscopy has been to improve spatial resolution. In recent years this historic goal has been achieved both in TEM and STEM. In our group we have demonstrated the direct sub-Angstrom imaging of a crystal lattice  and the spectroscopic identification of an individual impurity atom within one atomic column by electron energy loss spectroscopy . However, lateral resolution increases only linearly with available aperture angle, whereas depth resolution increases as the square of the aperture angle. Depth resolution is now comparable to typical specimen thicknesses, and with the next generation of aberration correctors, depth resolution will reach the nanometer level. This opens up a new method for 3D electron microscopy via optical sectioning, similar in principle to confocal optical microscopy. Applications of these techniques will be presented to hard materials such as structural ceramics, catalysts  and semiconductor device structures , and also to soft materials, including a conventional thin section of a mouse fibroblast cell line (3T3), providing 3D information of the membranes and filaments of the Golgi apparatus. In principle this method could be extended to EELS to provide a 3D analysis of electronic structure and composition.[1.] P.D. Nellist et al., Science 305 (2004) 1741.[2.] M. Varela et al., Physical Review Letters 92 (2004), Art. No. 095502.[3.] A. Y. Borisevich, A. R. Lupini, and S. J. Pennycook, P. Natl. Acad. Sci. USA 103 (2006) 3044. K. van Benthem et al., Applied Physics Letters 87 (2005) Art. No. 034104.
10:00 AM - KK1.2
Quantitative HAADF STEM and HRTEM Studies on Metallic Nano-Catalysts.
Long Li 1 , Laurent Menard 2 , Joo Kang 2 , Lin-Lin Wang 3 , Fengting Xu 1 , Huiping Xu 1 , Shang-Peng Gao 1 , Anatoly Frenkel 4 , Duane Johnson 3 , Ralph Nuzzo 2 , Judith Yang 1 Show Abstract
1 Materials Science and Engineering Department, University of Pittsburgh, Pittsburgh, Pennsylvania, United States, 2 Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, Illinois, United States, 3 Department of Materials Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois, United States, 4 Department of Physics, Yeshiva University, New York, New York, United States
10:15 AM - KK1.3
ADF-STEM Imaging of Strained GaN0.045As0.955 Epitaxial Layers on (100) GaAs Substrates.
Xiaohua Wu 1 , Michael Robertson 2 , James Gupta 1 , Jean-Marc Baribeau 1 , Craig Bennett 2 , Masahiro Kawasaki 3 , Toshihiro Aoki 3 Show Abstract
1 Institute for Microstructural Sciences, National Research Council of Canada, Ottawa, Ontario, Canada, 2 Department of Physics, Acadia University, Wolfville, Nova Scotia, Canada, 3 , JEOL USA, Peabody, Massachusetts, United States
The introduction of strain into epitaxial films can lead to enhanced performance in quantum well lasers such as lower threshold currents and higher differential gain due to strain induced changes in the electronic band structure. The incorporation of very small amounts of nitrogen into GaAs leads to a dramatic decrease in the bandgap energy and has enabled the growth of GaAs-based laser diodes functioning in the 1.3-1.55 μm range. The high angle annular dark field scanning transmission electron microscopy (HAADF-STEM, or Z-contrast) imaging technique has been successfully applied to various problems ranging from semiconductor interface determination to imaging individual dopant atoms to the observation of the atomic configuration of ultra-dispersed catalysts. ADF-STEM has established itself as an important technique for the atomic-resolution study of materials. However, very few detailed studies have been reported on the sensitivity of ADF-STEM image intensity to the effects of elastic strains in the specimen. Early studies of strain fields showed that strain always gave extra intensity (positive contrast) in ADF-STEM images. A recent ADF-STEM study of the interface between c-Si/a-Si suggested that the strain contrast depended closely on sample thickness and detector angle [Z. Yu, D.A. Muller and J. Silcox, J. Appl. Phy. 95 3362 (2004)]. Strain can cause not only positive contrast, but also negative contrast, and the strain contrast is always negative in HAADF-STEM images. In this study, a tensile strained GaN0.045As0.955 epitaxial layer on (100) GaAs is studied with a scanning transmission electron microscope (JEOL JEM-2100F, 200 kV, Cs = 0.5 mm). A series of ADF inner detector semi-angles ranging from 37 mrad to 90 mrad were used to form the ADF-STEM images. The strain always gave extra positive ADF-STEM intensity in the GaN0.045As0.955 layer, and the strong ADF-STEM image contrast between the low N-concentration strained GaN0.045As0.955 layer and the strain-free GaAs layer at the ADF detector semi-angle up to 65 mrad is striking. It was found that an ADF-STEM semi-angle larger than 75 mrad is needed to form atomic number contrast (Z-contrast) image with minimal strain contributions for the GaN0.045As0.955/GaAs system. Theoretical work using an atomic scattering theory and multi-slice simulations are employed in an attempt to explain the observed experimental results.
10:30 AM - **KK1.4
Advances in Aberration Correction for Transmission Electron Microscopy.
Bernd Kabius 1 , Maximilian Haider 2 Show Abstract
1 MSD, Argonne National Laboratory, Argonne, Illinois, United States, 2 , CEOS GmbH, Heidelberg Germany
During the last 10 years several aberration-correction concepts for electron microscopes have succeeded in improving spatial resolution and analytical capabilities [1, 2]. Electron optical systems for correction of spherical aberration are now a valuable tool for material science research and several investigations have already exploited some of the benefits of Cs-correction for high-resolution TEM and STEM. In addition to high resolution other TEM techniques can benefit from Cs-correction, such as energy filtered TEM (EFTEM). Examples of these applications will be shown. Further development of aberration correction technology follows two directions:- Correction of higher order aberrations such as fifth order spherical aberration is required for achieving interpretability at sub-Angstrom resolution (TEM) and higher beam currents (STEM). - Correction of chromatic aberration (Cc) has the capability of improving the information limit. This cannot be achieved with Cs-correction.The information limit can be improved alternatively by reducing the energy width of the electron emitter using a monochromator. One of the disadvantages of this concept is a strong loss of brightness due to the monochromator. Correction of chromatic aberration improves the damping envelope of temporal coherence without the need for a monochromator thus achieving higher contrast transfer and higher beam currents.Lens systems for the correction of chromatic aberration for TEM or STEM have not yet been implemented because of the stringent current stability requirements of about 10-8 for the multipole elements. Recently, new designs for chromatic aberration correction have been suggested by H. Rose  and this talk will concentrate on the novel design “Achroplanator” which is now under development. This corrector design is capable of correction of Cc and higher order axial aberration enabling aberration free imaging up to a resolution of 0.5Å at 200kV acceleration voltage in TEM mode which is one of the goals of the TEAM project. Based on this design study and recent progress improving the stability of power supplies Cc correction appears to be feasible with current technology. This novel corrector has the potential for high resolution TEM along high index zone axes and atomic resolution of amorphous or glassy materials. Further applications of Cc-correction for EFTEM and in situ experiments will be discussed. 1)Haider M, Uhlemann S, Schwan E, Rose H, Kabius B, Urban K, Nature 392 (1998) 768.2)Krivanek O.L., Delby N, Lupini A R, Ultramicroscopy 78 (1999) 1.3)Rose H, Nuclear Instruments & Methods in Physical Research, A519, (2004) 12.
11:30 AM - KK1.5
Controlling the Morphology of Stacked InAs/InP(001) Quantum Wires by Scanning - Transmission Electron Microscopy.
Teresa Ben 1 , David Sales 1 , Pedro Galindo 2 , David Fuster 3 , Yolanda González 3 , Luisa González 3 , Maria Varela 4 , Stephen Pennycook 4 , Sergio Molina 1 Show Abstract
1 Ciencia de los Materiales e Ing. Met. y Q.I., Universidad de Cádiz, Puerto Real , Cadiz, Spain, 2 Departamento de Lenguajes y Sistemas Informáticos, Universidad de Cádiz, Puerto Real, Cadiz, Spain, 3 Instituto de Microelectrónica de Madrid (CNM), CSIC, Tres Cantos, Madrid, Spain, 4 Condensed Matter Sciences Division, Oak Ridge National Laboratory, Oak Ridge , Tennessee, United States
11:45 AM - **KK1.6
Pushing the Limits in HRTEM towards Sub-Angstrom Materials Analysis.
Andreas Thust 1 , Juri Barthel 1 , Karsten Tillmann 1 , Chunlin Jia 1 , Lothar Houben 1 , Markus Lentzen 1 Show Abstract
1 Institut für Festkörperforschung, Forschungszentrum Jülich GmbH, Jülich Germany
The technique of high-resolution transmission electron microscopy (HRTEM) is experiencing remarkable progress at the present time. This progress is due to novel hardware components on the one hand, and due to novel software procedures on the other hand. Concerning the hardware components, the use of correctors for the spherical aberration (Cs-correctors) allows one to obtain atomically resolved images, which can be directly interpreted for the first time. The use of such correctors means a tremendous facilitation of materials analysis on an atomic scale. Successful experiments in the resolution regime well above 1 Angstrom are thereby possible on an almost daily basis. In addition, improvements of the mechanical and electrical instrument stability, together with the use of monochromators for the electron source, allow one even to access the sub-Angstrom resolution regime. However, quantitative sub-Angstrom work poses new rigorous technical challenges, since not only the availability of sub-Angstrom information as such is necessary, but also its unaltered transfer through the lens system in terms of lens aberrations. First, many additional lens aberrations, which have so far not been considered, can deteriorate the image contrast. Second, the precision of aberration measurement procedures used so far is no longer sufficient for the sub-Angstrom regime. Third, the time stability of lens aberrations becomes a crucial topic when aiming at the sub-Angstrom regime. At this point, the use of newly developed software procedures for aberration measurement plays a key role. With our newly developed ATLAS software it is possible to measure lens aberrations by more than an order of magnitude more precisely than previously possible. Additionally it is now possible to monitor the stability of the microscope's optical alignment. The measured data can be either used for an optimum alignment of the microscope before experiment, or for an a-posteriori aberration correction via digital image processing methods. The benefits of combining hardware Cs-correction with software reconstruction methods are demonstrated impressively by atomic-scale investigations of defects in semiconductors and electroceramic materials.
12:15 PM - KK1.7
Atomic Scale Characterization of thin Film Vanadium Based Perovskites.
Miaofang Chi 1 2 , Lane Martin 3 , Teruyasu Mizoguchi 4 , Ramamoorthy Ramesh 2 5 6 , Nigel Browning 1 7 Show Abstract
1 Department of Chemical Engineering and Materials Science, University of California, Davis, Davis, California, United States, 2 Institute of Geophysics and Planetary Physics, Lawrence Livermore National Laboratory, Livermore , California, United States, 3 Department of Materials Science and Engineering, University of California, Berkeley, Berkeley, California, United States, 4 Institute of Engineering Innovation, University of Tokyo, Tokyo Japan, 5 Materials Science Division, Lawrence Berkeley National Laboratory, Berkeley , California, United States, 6 Department of Physics, University of California, Berkeley, Berkeley, California, United States, 7 Materials Science and Technology Division, Lawrence Livermore National Laboratory, Livermore , California, United States
12:30 PM - KK1.8
Atomic Scale Characterization of Defects in YBCO Thin Films and Interfaces.
Lianfeng Fu 1 , Nigel Browning 1 2 , Williams Ramadan 3 , Darshan Kundaliya 3 , Satishchandra Ogale 3 , T. Venky Venkatesan 3 Show Abstract
1 Chemcial Engineering and materials science, University of California at Davis, Davis, California, United States, 2 Materials Science and Technology Division, Lawrence Livermore National Laboratory, Livermore, California, United States, 3 Center for Superconductivity Research, University of Maryland , College Park, Maryland, United States
YBa2Cu3O7-delta(YBCO or Y 123) superconductors have been considered to be one of the best candidates of the second generation high-temperature superconductor (HTS) wire to replace Bi2Sr2Ca2Cu3O8 for power supplies. To realize this application, a high critical current density (Jc), i.e. ~ 106 A/cm2 at 77k, is important. Because of the short coherence length (0.5-5 nm) in HTS materials, the percolation of supercurrent is susceptible to microscopic defects. Recent reports have indicated that grain boundaries, stacking faults, columnar defects, and inclusions can be effective pinning centers to improve Jc. However, the flux pining mechanism of microscopic defects is not completely understood. Heterostructures composed of a YBCO thin film (p-type superconductor) and another n-type oxide semiconductor are also of technological interest to develop new functional microelectronics devices. To ensure the superconductivity in YBCO thin films and their good rectifying proprieties in p-n junctions, the microscopic characterization of microscopic defects and interface in the heterostructures is of primary importance. Thin films of YBa2Cu3O7-delta studied in this work were grown on (001) SrTiO3 substrate doped with 0.1% wt% Nb by a pulsed laser deposition method with an excimer laser at 800 °C at an oxygen partial pressures of 200 mTorr. After the growth, the cross-section of thin film samples was characterized using high spatial resolution scanning transmission electron microscopy (STEM) Z-contrast imaging and electron energy loss spectroscopy (EELS) on a 200kV Schottky field-emission gun (FEG) FEI Tecnai F20. The atomically flat and chemically sharp p-n hetero-junction was confirmed by HR-STEM and EELS analysis. The Nb distribution was found to be uniform and unchanged across the interface, ensuring the high quality p-n junction heterointerface. We first observed the coexistence of 124 and 125 YBCO defect structure phases, appearing as planar defects in the YBCO thin film. These planar defects were thought to form with extra Cu-O planes related by a ½  glide symmetry. Dispersive Y2O3 nanoparticles with the size of 10-15 nm have also been observed in the thin film and confirmed by diffraction and EELS. The interaction of these planar defect structures and Y2O3 nanoparticles is thought to be beneficial for pining flux through the entire film thickness. The work was performed at the National Center for Electron Microscopy (NCEM), Lawrence Berkeley National Laboratory and supported by the DOE Contract No. DE-AC02-05CH11231 and NSF Grant No. DMR-04557660. We also acknowledge the funding under UMD NSF-MRSEC Grant No. DMR-00-80008 for thin film growth.
Monday PM, November 27, 2006
Fairfax A (Sheraton)
2:45 PM - **KK2.1
Cryo-electron Tomography of Mammalian Cells: 3D Insights for Tissue Engineering.
Andrew Leis 1 Show Abstract
1 Molecular Structural Biology, Max Planck Institute for Biochemistry, Munich Germany
Cryo- electron tomography (cryo-ET) enables 3-dimensional visualization of hydrated biological structures, currently at a resolution of about 5 nanometers. Vitrification makes it possible to introduce hydrated samples into the vacuum column of the electron microscope whilst simultaneously ensuring optimal preservation and immobilization of specimens at the molecular level. The value of cryo-ET as a tool for imaging biological architecture has been demonstrated convincingly for small bacteria and viruses; these can be imaged whole when contained within thin films of vitreous ice. The power of cryo-ET for molecular cell biology has not been realized fully due to the technical difficulties of vitrifying larger samples and the need to obtain high-quality, electron-transparent sections of specimens without compromising their vitreous character. This presentation will demonstrate the combination of 3D light and electron microscopy (confocal light microscopy and electron tomography, respectively) applied to 3 types of mammalian cells cultivated on several types of polymeric biomaterial. Initially, we demonstrated that embryonic stem cells, adenocarcinoma cells and cardiac muscle cell lines derived from mouse tissue could indeed be vitrified, which is mandatory for further analysis. To establish whether the stem cells had differentiated into mature cardiac muscle cells, a GFP-reporter coupled to the expression of myosin was used. Fluorescent cells in vitreous ice could then be pre-selected for cryo-ET to ensure that tomograms were obtained from the desired cell type. Three approaches were used to access the cell interior. In the first and simplest approach, cells were grown on carbon-coated EM sample grids, and tomograms were acquired from sufficiently thin regions. In the second approach, large quantities of cells growing in monolayers were detached from conventional tissue culture plastics by enzyme-treatment, vitrified by high-pressure freezing, and sectioned at -150°C prior to acquisition of tomograms. Although this method permits visualization in otherwise inaccessible regions of the cells, it has distinct disadvantages, namely disruption of the cytoskeleton, and an inability to relocate active cells in the EM. To create more realistic models of three-dimensional cell growth and interactions of cells with biomaterials, we grew cells on microcarrier beads prior to vitrification and sectioning, bypassing the need to detach cells from the growth substratum. As a final strategy and bridge to studies of tissue models ex vivo, we grew cells within three-dimensional, in vitro polymerisable peptide hydrogel matrices. Apart from the new insights into cell architecture including the spatial organization of microtubules, actin filaments and other macromolecular machines, these studies led to the first visualization of macromolecular complexes responsible for energy transduction as they are thought to occur in living cells.
3:15 PM - KK2.2
STEM 360 Degree Imaging and EELS Analysis of DNA Detection Assay Nanotechnology To Determine Local (Nano-scale) Material Properties.
Donovan Leonard 1 , Konrad Jarausch 2 , Marta Cerruti 3 , Gerd Duscher 1 , Stefan Franzen 3 Show Abstract
1 Materials Science and Engineering, North Carolina State University, Raleigh, North Carolina, United States, 2 Electron Microscopy Division, Hitachi High Technolgies America, Inc., Pleasanton, California, United States, 3 Chemistry, North Carolina State University, Raleigh, North Carolina, United States
4:30 PM - **KK2.3
Electron Tomography for the Characterization of Inorganic Nanostructured Materials.
Petra de Jongh 1 , Heiner Friedrich 1 , Jelle Sietsma 1 , A. Koster 2 , Krijn de Jong 1 Show Abstract
1 Inorganic Chemistry and Catalysis, Utrecht University, Utrecht Netherlands, 2 Electron Microscopy, Leiden University Medical Center, Leiden Netherlands
Transmission electron microscopy (TEM) is an indispensible technique to obtain detailed structural information on nanomaterials. An interesting class of nanostructured inorganic materials are heterogeneous catalysts. They consist of nanoporous materials, either being themselves the active phase, or with the active material distributed as nanosized crystallites inside the pores of the support material. For a detailed understanding of the preparation and functionality of these nanostructured materials, it is vital to be able to characterise the 3D pore structure and interconnectivity, and the location and accessibility of the active phase within the porous support. A major disadvantage of conventional TEM is that the obtained information is a 2D projection of the structural characteristics, and hence most of this essential information is missing. In this respect electron tomography (or 3D TEM) offers uniqe imaging capabilities, that can provide this detailed 3D information, not only qualitatively but also quantitatively . We will show several recent examples, and also discuss how the 3D TEM results are validated using complementary techniques such as XRD and nitrogen physisorption. A systematic study of the development of mesopores in zeolite crystals revealed that cavity-type mesopores (4-40 nm) are present in zeolite Y after steaming and acid leaching. The conversion of cavity-type to cylindrical mesopores called for special treatments that were beneficial for mass transfer of molecules in these zeolites. . It was a challenge to study the very complex structure of a commercial, sulfided Ni-Mo on Al2O3 hydrotreating catalyst. The spatial organization, morphology and orientation of the MoS2 particles in the pores were resolved, with an accuracy sufficiently high to display the 6 Å-spaced MoS2 planes. New information about the complex interconnected structure of the MoS2 within the mesopores of the alumina support was obtained .Recently we studied the distribution and accessibility of Ni(O) nanoparticles located inside ordered nanoporous SiO2. The regular pore ordening of the silica matrix allowed detailed and quantitative results on the distribution of the Ni(O) nanoparticles over the different pores and inside the pores, and yielded new insights into the effect of preparation parameters on the properties of the final catalytic material. A.J. Koster, U. Ziese, A.J. Verkleij, A.H. Janssen, and K.P. de Jong, J. Phys. Chem. B 104 (2000) 9368-9370  A.H. Janssen, A.J. Koster, and K.P. de Jong, Angew. Chem. Int. Ed. 40(6) (2001) 1102-1104 K.P. de Jong, L.C.A. van Oetelaar, E.T.C. Vogt, S. Eijsbouts, A.J. Koster, H. Friedrich, and P.E. de Jongh, J. Phys. Chem. B 110 (2006) 10209-10212
5:00 PM - KK2.4
Electron Tomography of SPM Probes and Nanoparticles.
Xiaojing Xu 1 , Guang Yang 1 , Zineb Saghi 1 , Yong Peng 1 , Beverley Inkson 1 , Ralph Gay 1 , Guenter Moebus 1 Show Abstract
1 Engineering Materials, University of Sheffield, Sheffield United Kingdom
5:15 PM - KK2.5
High Resolution Single and Dual Axis Tomography to Solve Materials Problems in Three Dimensions.
Ilke Arslan 1 , Jenna Tong 2 , John Walmsley 3 , Erling Rytter 3 , Edvard Bergene 3 4 , Paul Midgley 2 Show Abstract
1 , Sandia National Laboratories, Livermore, California, United States, 2 Materials Science and Metallurgy, University of Cambridge, Cambridge United Kingdom, 3 , Statoil Research Centre, Trondheim Norway, 4 , SINTEF Materials and Chemistry, Trondheim Norway
Nanotechnology now plays a key role across many fields of science, and especially materials science in furthering current environmental and semiconductor technology. Rather than analyzing and determining the properties of bulk single or poly-crystals where the third dimension is assumed to be uniform, we must now analyze materials that have a finite size and shape in three dimensions, and not necessarily uniform in any of the directions. This new demand on materials characterization has led to the development of electron tomography for inorganic materials using Z-contrast imaging in the scanning transmission electron microscope (STEM). Here we present high resolution single and dual axis tilt tomography results of Co-based Fischer Tropsch (FT) catalyst systems and CdTe tetrapods, respectively. We studied two Co-based catalyst systems with different supports to elucidate the size, shape, and distribution of the catalyst in its support in three dimensions. This nanoscale characterization gives us insight as to why one catalyst is more selective than the other. To study CdTe tetrapod structures, we must turn to dual axis tomography due to the geometry of the nanostructures. Their four thin, long legs in tetrahedral symmetry make it almost impossible to reconstruct all four legs with single axis tomography since one of the legs usually fall victim to the missing wedge. This new demonstration of dual axis tomography in materials science allows us to understand the structural properties of the tetrapods by studying their size, shape, and interaction with their support in three dimensions.
T. John Balk University of Kentucky
Andrew Minor Lawrence Berkeley National Laboratory
Alexandra Porter Cambridge University
Juergen Plitzko Max-Planck-Institute of Biochemistry
KK3: Advanced Techniques for Soft Materials
Tuesday AM, November 28, 2006
Fairfax A (Sheraton)
10:00 AM - **KK3.1
Advances in Electron Microscopy Techniques for the Characterization of Soft and Hard Materials.
Christian Kisielowski 1 Show Abstract
1 LBNL, NCEM, Berkeley, California, United States
The performance of electron microscopes improved significantly and aberration corrected TEM/STEM’s reach now towards deep sub Ångstrom spatial resolution combined with an energy resolution for spectroscopy of 100 meV. In this respect, the DoE’s Team Project is most noticeable (http://ncem.lbl.gov/team3.htm). Moreover, materials research efforts nowadays focus on investigations of hard and soft materials generating the need to characterize both material groups with similar performance. This talk highlights ongoing efforts at NCEM to establish electron microscopy as a facility tool for imaging and spectroscopy of soft and hard materials. PbSe nanocrystals and block copolymers are used as examples. A Libra 200 and a Tecnai F20 STEM/TEM are utilized for the study. Both instruments are equipped with a monochromator that enables refined spectroscopic studies. Electron tomography is performed with the Tecnai F20 while the Libra 200 is developed for the application of electron holography utilizing a phase plate. One goal of the investigations is to enable holographic electron tomography that is expected to boost the contrast of soft materials while minimizing radiation damage in the samples. Moreover, one can show that a data analysis in the framework of discrete tomography can further improve signal to noise ratios.
10:30 AM - KK3.2
Revealing Cellular and Nuclear Uptake of C60 into Human Macrophage Monocyte Cells using Energy-Filtered Transmission Electron Microscopy and Electron Tomography.
Alexandra Porter 1 , Mhairi Gass 2 , Karin Muller 3 , Jeremy Skepper 3 , Paul Midgley 4 , Mark Welland 1 Show Abstract
1 The Nanoscience Centre, University of Cambridge, Cambridge United Kingdom, 2 Daresbury Laboratory, UK SuperSTEM, Daresbury, Cheshire, United Kingdom, 3 Multiimaging Centre, Dept. Anatomy, University of Cambridge, Cambridge United Kingdom, 4 Department of Materials Science and Metallurgy, University of Cambridge, Cambridge United Kingdom
11:15 AM - **KK3.3
Probing the Hard-soft Interfaces in Self-assembled Protein Cage Architectures.
Trevor Douglas 1 Show Abstract
1 Department of Chemistry and Biochemistry, Montana State University, Boxeman, Montana, United States
The self-assembled architectures of viral capsids have been used as models for understanding processes of encapsulation of both hard and soft materials. We have explored modifications to the exterior and interior interfaces of viral (and other protein cage architectures) while maintaining assembly of stable icosahedral capsid particles. This has allowed us to utilize the high symmetry of the viral capsid to engineer unique functionality for highly ordered multivalent presentation for controlled nucleation of hard inorganic materials and packaging of soft organic materials. Of particular interest is the nature of the hard-soft interface in these systems. We have probed this interface using genetic and chemical modifications, spatially controlled inorganic synthesis, high-resolution transmission electron microscopy, and cryo-electron microscopy and image reconstruction to elaborate key features of the protein-inorganic interface. The role of protein interfaces in these assembled protein cage architectures has been explored to understand and exploit packaging of materials as diverse as nucleic acids, drugs, and inorganic nano-materials.
11:45 AM - KK3.4
Abnormal Mineralization of Mantle Dentin, as a Possible Cause of a Weak Dentino-enamel Interface in the MMP-20 Deficient Mouse Incisors.
Elia Beniash 1 , Ziedonis Skobe 1 , John Bartlett 2 Show Abstract
1 Biomineralization, Forsyth Institute, Boston, Massachusetts, United States, 2 Cytokine Biology, Forsyth Institute, Boston, Massachusetts, United States
12:00 PM - KK3.5
Microscopic Characterization of Biomimetic Hard Tissues and Their Biological Counterparts.
Matthew Olszta 1 2 , Sang Soo Jee 1 , Elliot Douglas 1 , Laurie Gower 1 Show Abstract
1 Materials Science & Engineering, University of Florida, Gainesville, Florida, United States, 2 Materials Science & Engineering, Penn State University, State College, Pennsylvania, United States
KK4/LL4: Joint Session: TEM Sample Preparation
Tuesday PM, November 28, 2006
2:30 PM - **KK4.1/LL4.1
Development of a Sample Preparation Method for Three-dimensional Structural and Elemental Analyses of a Specific Site and its Application.
Toshie Yaguchi 1 , Yasushi Kuroda 1 , Mitsuru Konno 1 , Takeo Kamino 1 , Kazutoshi Kaji 2 , Masashi Watanabe 3 Show Abstract
1 Naka Application Center, Hitahi High-Technologies Corporation, Hitachinaka-shi, Ibaraki, Japan, 2 Advanced Microscope systems design dept., Hitahi High-Technologies Corporation, Hitachinaka-shi, Ibaraki, Japan, 3 Dept. of Materials Science & Engineering, Lehigh University, Bethlehem, Pennsylvania, United States
Since demands for three dimensional structural and elemental analyses using transmission electron microscope (TEM) or scanning transmission electron microscope (STEM) are rapidly increasing and the analyses using the sample prepared by the conventional methods are becoming unsuitable for the demands, we developed a new sample preparation method. The instruments used in the method are the FB-2100 focused ion beam (FIB) system equipped with a FIB micro-sampling unit and the HD-2300 dedicated STEM. The sample is extracted from a specific site by the FIB micro-sampling technique and shaped into a pillar in the FIB system. The pillar shaped sample is then transferred to the specially designed specimen holder which allows 360 degree rotation and ± 20 degree tilting of a sample in both the FIB system and the STEM. Since the reduction of FIB damage layer is one of the important issues for high resolution image observation, a low energy Ar ion milling system (GENTLE-MILL HI) was employed in the final stage of a sample preparation. A pillar shaped Si single crystal specimen was Ar ion milled at 200V to remove the FIB damage layer. After the Ar ion milling, the crystal lattice fringes of the Si(110), (100), (1-10) planes are clearly observed. The technique was also applied to a three dimensional elemental distribution of As, Ti and N in a Si-device. Animation of rotation series of X-ray maps were made and it was used to reconstruct tomography demonstrating three dimensional elemental distributions at high precision.
3:00 PM - **KK4.2/LL4.2
Improving Localization and Sample Quality for S/TEM Analysis of Semiconductor Devices.
Richard Young 1 Show Abstract
1 , FEI Company, Hillsboro, Oregon, United States
3:30 PM - KK4.3/LL4.3
Site-Specific Investigation of Electrical Failure in Multilayer Ceramic Capacitors by FIB and TEM.
Gai-Ying Yang 1 , Paul Moses 1 , Clive A. Randall 1 , Elizabeth C. Dickey 1 Show Abstract
1 , The Pennsylvania State University, University Park, Pennsylvania, United States
3:45 PM - KK4.4/LL4.4
Focused Ion Beam Study of Ni5Al Single Splat Microstructure.
Yuhong Wu 1 , Meng Qu 1 , Lucille Gianuzzi 2 , Sanjay Sampath 1 , Andrew Gouldstone 1 Show Abstract
1 Materials Science and Engineering, Stony Brook University, Stony Brook, New York, United States, 2 , FEI Corp, Hillsboro, Oregon, United States
Thermally sprayed (TS) coatings are widely used for surface engineering across a range of industries, including aerospace, infrastructure and biomedical. TS materials are formed via the successive impingment, rapid quenching and build-up of molten powder particles on a substrate. The impacted ‘splats’ are thus the fundamental microstructural constituents of the coatings, and their intrinsic properties, as well as intersplat bonding and morphology, dictate coating behavior. Beyond the obvious practical considerations, from a scientific standpoint, splats represent a fascinating template for study, due to the highly non-equilibrium processing conditions (rapid deceleration from sub-sonic velocities, million-degree/sec cooling rates). In the literature, many studies of isolated splats on substrates have been carried out, but these have focused on overall morphology (disc-shape vs fragmented). Direct observations of microstructure, in particular cross-section, are limited in the specimen preparation stage due to splat size (tens of microns in diameter, 1-2 microns in thickness). However, Focused Ion Beam (FIB) techniques have allowed this problem to be addressed in a robust manner; in this talk we will discuss such approaches to observe Ni5Al splats on stainless steel substrates. Cross-sections through the splat and the substrate were created by recourse to ion milling and the ion beam itself provided good channeling contrast for grain imaging. The typical splat microstructure with sub-micron Ni(Al) columnar grains, a chill zone at the bottom and a lift off area is observed in high detail. In addition, an amorphous aluminum oxide top layer of 100-200 nm is partially present on top of the Ni(Al) columnar grains. At the splat/substrate interface, defects such as micro- and nano-scale pores were characterized for the first time and will be discussed. These observations provide insights into splat and interface formation during the deposition process and may drastically improve our current understanding of Ni5Al splat properties.
4:30 PM - **KK4.5/LL4.5
A Comparison of Quantification of Microstructural Features in α/β-Ti alloys using Stereologically-based and Direct Three-dimensional Characterization Techniques.
Hamish Fraser 1 Show Abstract
1 , Ohio State University, Columbus, Ohio, United States
Traditionally, microstructural features have been characterized by first recording images from two-dimensional (2-D) sections and then using stereological techniques to yield information from these 2-D sections in three-dimensions (3-D). More recently, new instruments such as the dual-beam FIB (DB-FIB) have permitted serial sectioning of samples such that 3-D representations of features may be derived directly. It is important to both validate these new techniques and determine the fidelity of the resulting reconstructions. As part of this validation, the results of materials characterization employing traditional stereological techniques will be compared with those provided by direct 3-D characterization using the DB-FIB. The samples to be characterized are taken from a heat-treatment study of two Ti alloys, namely the binary Ti-xMo system and the α/β alloy Timetal 550 (Ti-4Al-4Mo-1Zr-1Sn, wt%). The samples have been characterized using optical microscopy and scanning electron microscopy (SEM). Several of the important microstructural variables that influence mechanical properties (volume fraction α, α-lath thickness (μm), prior β grain factor (μm2/μm3), volume fraction of colony α, and width of grain boundary α), have been quantified using a set of rigorous stereological procedures for two-dimensional images. These features have been characterized in directly in 3-D using serial sectioning in the DB-FIB. The results derived from these two characterization techniques will be compared and contrasted. The validity of the new direct 3-D characterization techniques will be defined.
5:00 PM - KK4.6/LL4.6
FIB Specimen Preparation for TEM Studies of Diamond-SiC Interface Structure.
Joon Seok Park 1 , Robert Sinclair 1 , David Rowcliffe 2 , Margaret Stern 3 , Howard Davidson 4 Show Abstract
1 Materials Science and Engineering, Stanford University, Stanford, California, United States, 2 , Skeleton Technologies, Los Osos, California, United States, 3 , Sun Microsystems, San Diego, California, United States, 4 , Isothermal Research Systems, Mountain View, California, United States
5:15 PM - KK4.7/LL4.7
Focused Ion Beam Processing of Nanocomposite and 3-D Nanostructured Soft Materials.
Steven Kooi 1 , Vahik Krikorian 1 2 , Ji-Hyun Jang 1 2 , Cheong Koh 1 , Edwin Thomas 1 2 Show Abstract
1 Institute for Soldier Nanotechnologies, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States, 2 Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States
The complete structural and compositional characterization of nanocomposite / nanostructured materials by transmission electron microscopy (TEM) and atomic force microscopy (AFM) methods is commonly hampered by sample preparation issues. When standard TEM sample preparation techniques, namely cryo-microtoming, are applied to nanocomposite materials, they often fail to produce representative samples that are uniform and thin enough to be electron transparent. Microtoming a material composed of hard nanoparticles, carbon nanotubes, or clay platelets dispersed in a soft polymer matrix often leads to problems where the hard additive will be pulled out of the soft matrix and/or the soft matrix will be distorted or damaged during the cutting process. In addition, microtoming techniques are not applicable to organic thin films supported on hard substrates. This limits the characterization of supported organic / polymer films as well as organo-electronic devices where the investigation of the interfaces between the polymer and substrate or electrode are of great interest. Microtoming as well as cryo-fracturing techniques are also used in an attempt to prepare samples of internal surfaces that are sufficiently flat enough for phase contrast AFM measurements of their microstructure. However, the microtomed surfaces typically show plastic flow from the cutting process and cryo-fractured surfaces may only be flat in a small fraction of the total surface area.In order to get around the problems mentioned above, we have optimized focused ion beam (FIB) techniques for use with soft materials including nanocomposites and supported organic films to produce both electron transparent and smooth samples for TEM and AFM respectively. As an illustrative test case we have produced multilayered polymer films with alternating layers containing hard nanoparticles supported on a silicon substrate. This type of material can not be microtomed successfully. Scanning electron microscope (SEM), TEM, and AFM measurements will be presented for samples prepared from these multilayered and multicomponent supported films to demonstrate the applicability of FIB processing to soft nanocomposite materials. In addition, results from FIB prepared samples of block-copolymer thin films, clay nanocomposite materials, conducting polymer films, and organo-electronic devices will be presented along with a discussion of possible beam induced damage and gallium contamination during FIB sample preparation.FIB techniques have also been applied to help characterize 3D structured polymeric materials produced by multibeam laser interference lithography techniques. The properties of these structured polymers are highly dependent on the quality of their full three dimensional structure. FIB is used to produce and image multiple consecutive cross sectional samples of these materials and the images are used to reconstruct the overall 3D structure.
5:30 PM - KK4.8/LL4.8
Insights on Nano-oxidation Kinetics by Combined High Resolution Spatial and Spectral Electron Microscopy of the Dynamically Formed Cu2O /Cu Interfaces.
Xuetian Han 1 , Ana Hungria 2 , Jon Barnard 2 , Paul Midgley 2 , Judith Yang 1 Show Abstract
1 Materials Science and Engineering, University of Pittsburgh, Pittsburgh, Pennsylvania, United States, 2 Department of Materials Science and Metallurgy, University of Cambridge, Cambridge United Kingdom
T. John Balk University of Kentucky
Andrew Minor Lawrence Berkeley National Laboratory
Alexandra Porter Cambridge University
Juergen Plitzko Max-Planck-Institute of Biochemistry
KK5: Polymer Microscopy
Wednesday AM, November 29, 2006
Fairfax A (Sheraton)
10:15 AM - **KK5.1
Imaging Nanostructured Block Copolymer Electrolytes Using Electron Microscopy.
Nitash Balsara 1 2 , Mohit Singh 1 2 , Moon Jeong Park 1 2 , Enrique Gomez 1 2 Show Abstract
1 Chemical Engineering, University of California, Berkeley, Berkeley, California, United States, 2 , Lawrence Berkeley National Laboratory, Berkeley, California, United States
10:45 AM - KK5.2
Determination of the Extent of Lateral Spread and Secondary Nucleation Density in Isotactic Poly(vinylcyclohexane) Single Crystals. An Original Means to Investigate Polymer Crystal Growth.
Bernard Lotz 1 , Daniel Alcazar 1 4 , Akiyoshi Kawaguchi 2 , Annette Thierry 1 , Stephen Cheng 3 , Edwin Thomas 4 Show Abstract
1 , Institut Charles Sadron (CNRS - ULP), Strasbourg France, 4 Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States, 2 Faculty of Science and Engineering, Ritsumeikan University, Shiga Japan, 3 Maurice Morton Institute and Department of Polymer Science, The University of Akron, Akron, Ohio, United States
Crystallizable polymers assemble in spherulitic semicrystalline structures made of radiating lamellae. Direct investigation of the mechanism of lamella formation in the bulk has remained a challenge up to this date. Polymer crystallization from solution yields monolamellar single crystals that provide a simpler, more accessible, structural system, yet that can be analyzed with the same mechanistic growth concepts as used for lamellae crystallized from the bulk. Analysis of single crystal growth in terms of surface deposition events, secondary nucleation and lateral spread, can be considered as representative of polymer crystallization in general. The extent of lateral spread has become a fundamental parameter in polymer crystallization theories. However, only indirect estimates of the lateral spread are available. The absence of any direct measurement of surface chain deposition event stems from the fact that, as a rule, once the chain becomes part of the crystal, no internal characteristic helps differentiate a stem or group of stems from the rest of the crystal.Isotactic poly(vinylcyclohexane) is a polyolefin that builds up single crystals with twinned growth sectors. Twinning by merohedry is a mild perturbation that keeps the unit-cell orientation and has little impact on the growth process, yet generates domains that can be mapped via dark-field imaging in transmission electron microscopy. Thus, twinned deposition on the growth face becomes an original probe for polymer crystallization. The lateral size of the domains, associated with a twinned lateral spread from a twinned secondary nucleation, helps measure the lateral spread extent and secondary nucleation density during crystal growth. The extent of lateral spread has been determined for single crystals produced in squalane over a wide range of crystallization temperatures (Tc). The average lateral spread extent ranges from 35 to 60 nm (one stem ≈ one nm) at 120 °C and 220 °C, respectively and the distributions broaden at high Tc. By inference, average secondary nucleation densities range from 30 to 15 microm.-1 at low and high Tc, respectively.The observed trends for lateral spread extent and the possibility to link the internal structure of twinned domains with the crystal morphology at different crystallization temperatures confirms that the most efficient deposition sites have the lowest surface energy barriers. This is clearly a surface recognition process. Twinning by merohedry as illustrated here for isotactic poly(vinylcyclohexane) is an original probe that allows direct investigation of surface deposition events in polymer crystal growth. It provides the first set of data that illustrates and quantifies the variation of lateral spread extent and secondary nucleation density with crystallization temperature.
11:30 AM - **KK5.3
The Nanoscale Morphology of Hydrated Soft Materials.
Matthew Libera 1 Show Abstract
1 Dept. of Chemical Engineering, Stevens Institute of Technology, Hoboken, New Jersey, United States
Water plays a key role in the performance of many advanced polymers such as resorbable polymeric biomaterials for tissue-engineering and drug-delivery applications. In these materials, the amount and spatial distribution of water plays a defining role in the degradation and erosion that is central to their performance in vivo. Historically, the transmission electron microscope (TEM) has been a powerful tool for studying nanoscale morphology of soft materials, but the traditional methods of TEM imaging are insufficient to comprehensively establish the morphology of multicomponent polymers that contain water. We have been developing new approaches to quantitatively map the composition of hydrated/solvated polymers and tissue using spatially resolved electron energy-loss spectroscopy (EELS) in the scanning transmission electron microscope (STEM). Because low-loss EELS spectra are very sensitive to valence electron structure, they can chemically differentiate between various polymers. By incorporating cryogenic TEM techniques, this method can be used to not only measure the nanoscale spatial distribution of different polymer species in a material but also that of water and other solvents. We have applied spatially resolved EELS in the cryo-STEM to quantitatively map the early-stage morphological changes in a degrading and eroding random copolymer of DTE (desaminotyrosyl-tyrosine ethyl ester) and PEG (poly(ethylene glycol)). This polymer comes from a combinatorial library of tyrosine-derived polycarbonates being developed for biomedical device applications. The total water content gradually increases when this polymer is immersed in water for five months, but we resolve no morphological changes. The oligomeric degradation products remain trapped within the bulk of the polymer. After 12 months of exposure to water, however, features with characteristic dimensions on the order of 50-100 nm can be observed, and quantitative EELS indicates that these are enriched in water and depleted in PEG. Spectroscopic imaging together with image simulation indicate that a percolated network of high-diffusivity pathways at nanolength scales has developed which plays a key role in the subsequent bioresorption of this bulk-eroding polymer. These findings suggest new ways to tune bioresorption based not only on polymer composition but also on the underlying polymer morphology, and they point to the significance of this novel approach to imaging the nanoscale morphology of solvated polymers.
12:00 PM - KK5.4
EELS Analysis of Organic Semiconductors in TEM.
Elena Tchernychova 1 , Werner Grogger 1 , Evelin Fisslthaler 2 , Emil List 2 , Meltem Sezen 1 , Peter Pölt 1 , Ferdinand Hofer 1 Show Abstract
1 Research Institute for Electron Microscopy, Graz University of Technology, Graz Austria, 2 Institute of Solid State Physics, Graz University of Technology, Graz Austria
The development of polymer-based multilayered optoelectronic devices in small dimensions requires a thorough understanding of the optical and electronic properties of the employed organic semiconducting materials. Among available techniques, electron-energy loss spectroscopy (EELS) in transmission allows the best compromise between energy and spatial resolution for probing the local electronic and chemical structure of polymer layers. However, this technique is also known to produce considerable physical and chemical changes in the polymer structure due to the inelastic scattering of fast incident electrons. Therefore, the conditions for obtaining reliable EELS data should be first optimized using plain unprocessed organic semiconductors as TEM test specimens.For EELS investigations an FEI Tecnai F20 (field emission gun) microscope operated at 200 kV and equipped with monochromator, STEM-unit, high-resolution GIF, and 2k×2k CCD camera was employed. The energy resolution was 0.7 eV in the non-monochromated mode and 0.2 eV in the monochromated mode. The TEM test specimens were produced by spinning polymers in solution over the NaCl crystal, which was later dissolved in water and the pieces of polymers were caught onto regular TEM Cu-grids. The typical thicknesses of the polymer films were estimated to be ~50nm.The main problem addressed in the present study is the appearance of degradation during TEM analysis of poly(3-hexilthiophene) (P3HT) and polyfluorene (PF) conjugated polymers, which are applicable in organic light-emitting diodes (OLEDs) and organic field-effect transistors (OFETs). The changes in the chemical structure of the polymers were monitored at the C K edge, where the electron dose dependent degradation of the π* peak, which corresponds to the C=C bonds, was observed both at ambient- and cooled down to liquid nitrogen temperatures. The degree and the progress of degradation were quantitatively estimated after the extraction of spectrum peaks from the deconvoluted and background subtracted C K spectra. In addition, the low-loss region of the EELS spectra was used for monitoring changes in the extracted dielectric function of the polymers, which are caused by the exposure to the incident electrons. Lastly, the utilization of the results obtained for the TEM test specimens makes it possible to perform further reliable EELS analysis of the polymer semiconducting layers in OLED and OFET devices in both high- and low-loss regions of the spectrum.
12:15 PM - KK5.5
Phase Behavior of Amphiphilic Triblock Copolymers (PAA-b-PMA-b-PS) in Mixed Solvents via Electron Microscopy and Neutron Scattering.
Kelly Hales 1 , Honggang Cui 1 , Zhiyun Chen 2 , Karen Wooley 2 , Darrin Pochan 1 Show Abstract
1 Department of Materials Science and Engineering and Delaware Biotechnology Institute, University of Delaware, Newark, Delaware, United States, 2 Center for Materials Innovation and Department of Chemistry, Washington University in Saint Louis, Saint Louis, Missouri, United States
The characterization and understanding of the bulk phase behavior of the amphiphilic triblock copolymers of poly(acrylic acid)-b-poly(methyl acrylate)-b-poly(styrene) in water/tetrahydrofuran (THF) solvent mixtures is strongly dependent on block composition as well as solvent composition. The length of the acrylic acid block and the methyl acrylate block were held constant for each copolymer while the polystyrene block length was varied. The block copolymers were dissolved in THF in the presence of a divalent, organic counterion. Upon the slow addition of water, a variety of unique structures were observed including phase-separated nanoparticles, bulk-like lamellar phase separation, spherical micelles, cylindrical micelles, disks, as well as toroidal (ring-like) assemblies. The specific structure formed was dependent on the architecture of the triblock copolymer, the amount of counterion present, and the water to THF volume ratio. This talk will focus on the structure of polymer nanoparticles and networks formed in low water content systems. The size of the nanoparticles and whether separated nanoparticles vs. an interconnected network was formed can be controlled via solvent composition. Importantly, both the nanoparticles and network phases contain their own inherent nanostructure due to local phase separation of the block copolymers. Cryo-transmission electron microscopy and small-angle neutron scattering were critical to unambiguously characterizing the morphologies of these copolymers in situ. The structures were confirmed with cast films examined via traditional transmission electron microscopy.
12:30 PM - KK5.6
Phase Contrast HRTEM and HAADF-STEM Electron Tomography Reconstructions of Polymer/ Layered Silicate Nanocomposites.
Lawrence Drummy 1 , Hilmar Koerner 2 , Y. Wang 3 , B. Farmer 1 , Richard Vaia 1 Show Abstract
1 AFRL/ML, Air Force Research Laboratory, Wright Patterson AFB, Ohio, United States, 2 , Universal Technology Corporation, Dayton, Ohio, United States, 3 , FEI Company, Hillsboro, Oregon, United States
KK6: In-situ TEM
Wednesday PM, November 29, 2006
Fairfax A (Sheraton)
2:45 PM - **KK6.1
Nanosecond Microscopy of Hard and Soft Materials with the Dynamic Transmission Electron Microscope.
Geoffrey Campbell 1 , Michael Armstrong 1 , Nigel Browning 1 , Judy Kim 1 , Wayne King 1 , Thomas LaGrange 1 , Bryan Reed 1 Show Abstract
1 Chemistry & Materials Science, Lawrence Livermore National Lab, Livermore, California, United States
The dynamic transmission electron microscope uses an electron source operating by photoemission driven with a pulsed ultra-violet laser. The pulsed electron bunches enter the electron microscope, which operates essentially identical to normal operation but now with relatively high instantaneous currents of several mA. The microscope is fitted with a second laser that is used to interact with the specimen for performing pump-probe experiments. The relative timing of the specimen pump and electron probe is simply set by the relative timing of the two laser pulses. The electron pulse has a duration of 30 ns and up to 107 electrons can be collected at the CCD detector in the form of either an image or a diffraction pattern. The high currents cause electron-electron interactions that tend to blur the image, however we have demonstrated 20 nm spatial resolution in the imaging mode at 30 ns pulse duration. We have applied this technique to the study of martensitic transformations in metals (hard material), which allows us a detailed study of the transformation kinetics in thin foils. We have also applied it to the study the linked molecular conformation and crystal structure transition in HMX, an organic molecule (soft material). We have also studied the progression of chemical reactions in the solid state in reactive multilayer thin films.This work performed under the auspices of the U.S. Department of Energy, Office of Basic Energy Sciences by University of California, Lawrence Livermore National Laboratory under Contract W-7405-Eng-48.
3:15 PM - KK6.2
In-situ Studies of the α to β Transition in Ti Using the Dynamic Transmission Electron Microscope: Nanosecond Observations of the Nucleation and Growth Behavior in Nanocrystalline and Coarse-grained Material.
Thomas LaGrange 1 , Geoffrey Campbell 1 , Nigel Browning 1 2 , Wayne King 1 Show Abstract
1 Materials Science and Technology Division, Chemsitry and Materials Science Directorate, Lawrence Livermore National Laboratory, Livermore, California, United States, 2 Chemical Engineering and Materials Science, Universtiy of California-Davis, Davis, California, United States
3:30 PM - KK6.3
Kinetics of the β-δ Phase Transition in HMX Studied Using Dynamic Transmission Electron Microscopy.
Michael Armstrong 1 , Alan Burnham 1 , Thomas Lagrange 1 , Bryan Reed 1 , Ben Torralva 1 , Wayne King 1 Show Abstract
1 , Lawrence Livermore Nat'l Lab, Livermore, California, United States
The β-δ phase transition kinetics of nitramine octahydro-1,3,5,7-tetranitro-1,3,5,7- tetrazocine (HMX) have been the subject of study for decades , yet many aspects of this complicated phase transtion remain a mystery. HMX is molecular crystal commonly used as an explosive in the construction of detonators and rocket propellant. The phase transition is temperature driven, and involves a conformation change of the molecule from a “chair” to a “boat” conformation, accompanied by a crystal structure change from monoclinic to hexagonal, a 7% volume change, and significant changes in the morphology of the crystal. Although this phase transition is kinetically driven, the details of the nucleation and growth process currently are poorly understood and cannot be accurately modeled. There is enough disagreement in the fundamental physical parameters of the phase transition, such as the transition temperature, that it is difficult to find consensus on the underlying mechanisms.To address these issues, we will present data regarding the β-δ phase transition in HMX observed via Dynamic Transmission Electron Microscopy (DTEM) . DTEM is essentially fast, time-resolved electron microscopy. In analogy with pump-probe optical spectroscopy, HMX samples are heated by a short laser pulse (< 100 ns) and then probed with a short electron pulse (also < 100 ns) after a time delay. Several experiments may be performed with different delays between the pump and probe, allowing the construction of a time-resolved “movie” (composed of either images or diffraction patterns) which characterizes the evolution of the sample while it undergoes the phase transition. In order to precisely quantify kinetics and the physical processes in the β-δ phase transition, we will present the results of pump probe diffraction and imaging experiments in the DTEM. Diffraction experiments quantify the ratio of β/δ as a function of time, and provide information about intermediate states along the phase transition pathway. Imaging experiments provide a complete spatial picture of the nucleation and growth kinetics - a direct nanoscopic view of nucleation events and subsequent growth of phase transformed regions with 30 ns time resolution and 20 nm spatial resolution.This work was performed under the auspices of the U.S. Department of Energy by the University of California, Lawrence Livermore National Laboratory under Contract W-7405-Eng-48.1. T. B. Brill and R. J. Karpowicz, Journal of Physical Chemistry 86 (1982) 4260-42652. T. B. LaGrange et al., accepted Applied Physics Letters (2006)
4:15 PM - **KK6.4
In-situ electron microscopy: A Versatile Tool to Study Mechanical Size Effects.
Gerhard Dehm 1 , Sang Ho Oh 1 , Daniel Kiener 1 Show Abstract
1 Material Physics, Erich Schmid Institute of Materials Science and Montanuniv. Leoben, Leoben Austria
4:45 PM - KK6.5
Quantitative in situ TEM Mechanical Testing- a Window into Nanomechanics.
Zhiwei Shan 1 , Andrew Minor 1 , Syed Asif 2 , Oden Warren 2 Show Abstract
1 , Lawrence Berkeley National Laboratory, Berkeley, California, United States, 2 , Hysitron Incorporated, Minneapolis, Minnesota, United States
5:00 PM - KK6.6
Elongation and Rupture of Metal Alloy Nanowires.
Jefferson Bettini 2 , Fernando Sato 1 , Paulo Coura 3 , Socrates Dantas 3 , Douglas Galvão 1 , Daniel Ugarte 1 2 Show Abstract
2 Lab. Microscopia Eletrônica, Lab. Nac. Luz Síncrotron, Campinas, SP, Brazil, 1 Física Aplicada, IFGW-UNICAMP, Campinas, SP, Brazil, 3 Física, Univ. Fed.de Juiz de Fora, Juiz de Fora, MG, Brazil
5:15 PM - KK6.7
Elongation of Carbon Fullerene in High-electric Field.
Yoshifumi Oshima 1 3 , Yoshihiko Kurui 2 , Makoto Yoshida 2 , Kunio Takayanagi 2 3 Show Abstract
1 Materials Science and Engineering, Tokyo Institute of Technology, Yokohama, Kanagawa, Japan, 3 CREST, Japan Science and Technology Corporation, Kawaguchi, Saitama, Japan, 2 Condense Matter Physics, Tokyo Institute of Technology, Tokyo, Tokyo, Japan
Atom transfer and molecule manipulation in high-electric field are very interesting phenomena from fundamental and technological point of view. Theses phenomena have been investigated mainly by scanning tunneling microscope (STM). However, it is difficult to estimate the distance between an electrode surface and a STM tip or the distance between an electrode surface and a molecule. Also, it is possible to deform atomic structure in the vicinity of the gap due to high-electric field. In this study, we investigated atomic structure of gold electrode and a carbon fullerene adsorbed on a gold STM tip simultaneously with the tunneling current using our developed transmission electron microscope combined with mechanical controllable breaking junction (TEM-MCBJ).Using TEM-MCBJ, we can obtain TEM image simultaneously with current measurement. TEM images are recorded at TV rate (30 frames per 1 second) and current values are recorded at 100 sampling per each frame (3 k Hz). The accuracy is 0.1% in the range of 0.1 nA to 10 μA. The current measurement is synchronized with TEM observation by video trigger signal. The gold electrode and tip were synthesized by approach-retract cycles using piezo actuator. Strong electron beam irradiation made their surface clean. A single carbon fullerene was made of residual carbon-based molecules adsorbed on the electrode surface by applying the bias voltage of 1 V when the tip approached to the electrode with 1 nm gap. In this observation, the carbon fullerene was estimated to be C240, since the apparent width was about 1.35 nm in TEM image.The tunneling current was about 1 nA when the gap distance between the top of the carbon fullerene and the edge of the electrode was about 0.8-0.9 nm. During approaching the gold tip to the carbon fullerene adsorbed on the electrode, the tunneling current increased exponentially with the gap distance. Since the slope on the logarithm of the tunneling current against the gap distance was about 15 -16, the barrier height was estimated to be 2.2-2.4 eV. We, furthermore, found that the size of the carbon fullerene elongated along the applied electric field just before it had contact with the gold tip. Such elongation was not observed till the gap distance was 0.4 nm. The apparent width was 1.35 nm in constant. On the other hand, it abruptly increased just before the contact and became 1.5 nm. This elongated carbon fullerene had a contact with the tip and had 0.4-0.6 G0 (=2e2/h; quantized unit of conductance) in conductance.
5:30 PM - KK6.8
Kink Motion in Carbon Nanotubes.
Jianyu Huang 1 , S. Chen 1 , Z. Ren 1 , Z. Wang 1 , D. Wang 1 , M. Vaziri 2 , Z. Sou 3 , G. Chen 4 , M. Dresselhaus 5 Show Abstract
1 Department of Physics, Boston College, Chestnut Hill, Massachusetts, United States, 2 Department of Physics, University of Michigan-Flint, Flint, Michigan, United States, 3 Division of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts, United States, 4 Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States, 5 Department of Physics, and Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States
The plastic deformation mode of carbon nanotubes remains unknown after over a decade since their discovery. Here we report that kink motion is the major plastic deformation mode in all nanotubes when being tensile-loaded at high temperatures [1,2]. The kink motion, observed inside a high resolution transmission electron microscope, is strikingly reminiscent of dislocation motion in crystalline materials: namely, it dissociates and multiplies. The kinks are nucleated from vacancy creation and aggregation, and propagate in either a longitudinal or a spiral path along the nanotube walls. Remarkably, the kink migration velocity (0.1~10 nm/s) is very close to that of the thermal fluctuation-induced double kinks in a dislocation line, indicating nanotube kink motion mimic dislocation kinks crossing the periodic Peierls hills in the honeycomb lattice of graphite.  J.Y. Huang et al., Phys. Rev. Lett. 94, 236802 (2005). J.Y. Huang et al., Nature 439, 281 (2006).
KK7: Poster Session
Wednesday PM, November 29, 2006
Exhibition Hall D (Hynes)
9:00 PM - KK7.1
Nanoscale Plastic Deformation and Fracture of Polymers Studied by in situ Nanoindentation in a Transmission Electron Microscope.
Jing Zhou 1 , Kyriakos Komvopoulos 1 , Andrew Minor 2 Show Abstract
1 Mechanical Engineering Department, UC Berkeley, Berkeley, California, United States, 2 National Center for Electron Microscopy, Lawrence Berkeley National Laboratory, Berkeley, California, United States
9:00 PM - KK7.10
Dynamic Volume Change Investigation of Organic Materials in ESEM.
Xiaohu Tang 1 , Mario de Rooij 1 Show Abstract
1 , Delft University of Technology, Delft Netherlands
Moisture transport is one of the most important phenomena in organic materials in a variety of fields. As the result of this process in the fields of biology, polymer, food, and agriculture, volume change like swelling and shrinkage have received a lot of theoretical and experimental attention. However, many questions remain about the nature and behavior of moisture hydration and dehydration because of the limitations of the experimental techniques to study it. Although many methods are available to measure the static volume change both directly and indirectly in equilibrium, for example tilting sample stage in ESEM to make stereoscopic images, it is difficult to determine in situ the volume evolution during relative humidity (RH) changing, especially at the beginning of RH change due to the time limitation to tilt the stage without introducing additional errors. We describe here a procedure that provides a rapid way to investigate volume change as the function of relative humidity and time.
9:00 PM - KK7.11
Micrograph Segmentation: A Comparative Approach.
Andrea Bianchi 1 , Luciano Costa 1 , Roberto Lotufo 2 Show Abstract
1 Department of Physics, Institute of Physics of Sao Carlos, Sao Carlos, Sao Paulo, Brazil, 2 Department of Computer Engineering and Industrial Automation, Faculty of Electrical and Computer Engineering - UNICAMP, Campinas, Sao Paulo, Brazil
9:00 PM - KK7.12
Local Bonding Analysis of Heavy Element Based Metal-gate/insulator Interface by Means of TEM-EELS.
Hiroki Tanaka 1 , Reika Ichihara 1 , Yoshinori Tsuchiya 1 , Masato Koyama 1 , Shiro Takeno 1 Show Abstract
1 , Toshiba Corporation, Yokohama Japan
9:00 PM - KK7.13
Determination of Inelastic Mean Free Path and Energy-Loss Function by Electron Energy-Loss Spectroscopy in TEM: A Model Study Using Si and Ge.
Chongmin Wang 1 , Bret D. Cannon 1 Show Abstract
1 , Pacific Northwest National Laboratory, Richland, Washington, United States
A key process in the energy cascade that underlies the operation of radiation detectors is excitation of plasmons, where plasmons are a collective motion of the valence electrons in a solid, which decay into electron-hole pairs and heat. The plasmon excitation cross section can be determined by measuring the electron mean free path corresponding to the plasmon scattering, L. The probability P(t) for transmission of an electron with energy loss E = nEp through a thin foil specimen with thickness t can be described by the joint probability that the electron is transmitted, detected, and produces n plasmon excitations. The first two factor are independent of n while the later probability distribution is given by the Poisson distribution, P(t) = (t/L)^n exp(-t/L)/n!, where n = 0 corresponds to no or only elastic scattering and n = 1, 2, … , corresponds to the 1st , 2nd , etc. plasmon losses. The area of a specific plasmon loss peak normalized by the overall low loss peak area gives Pn(t) and hence the ratio t/L. Measurement of this ratio for various specimen thicknesses will allow the determination of plasmon loss mean free path and mean cross section for plasmon excitation. Critical for this determination of Lp is accurate measurement of the specimen thicknesses at the points at which the energy loss spectra were acquired. Although the inelastic mean free path for Si and Ge have been measured previously, reported experimental values for silicon range from 121 nm to 160 nm for 200 keV and a large collection angle. A key factor responsible for this uncertainty is the lack of an accurate measurement of the specimen thickness at the point at which the EELS spectra are obtained. In this research, we have evaluated a systematic methodology for determination of the specimen thickness. In the thickness measurement based on converging beam electron diffraction, CBED, instead of the classic “trial and error” straight-line-fitting method to either the maxima or minima, a non-linear least square fitting of the theoretical diffraction profile to the energy filtered two-beam CBED is used. The low-loss EELS spectrum is also obtained from the same location. The inelastic mean free path was determined using the measured thickness and EELS data. Furthermore, attempt is also made to obtain the dielectric function from the low-loss spectrum. The established method will extended to other materials and the results will be compared with numerical simulations.
9:00 PM - KK7.14
High Resolution Transmission Electron Microscopy of Carbon Nanotubes: Darkfield, Brightfield, and Energy-filtered Image Profiles.
Sanju Gupta 1 , Eric Mandell 2 , Shuhan Lin 2 , Phil Fraundorf 2 Show Abstract
1 Physics and Materials Science, Missouri State University, Springfield, Missouri, United States, 2 Physics, University of Missouri, Saint Louis, Missouri, United States
Nanocarbons in its various forms, specifically nanotubes, may become a key material for the manufacturing of electronic and mechanical devices in the 21st Century. Nevertheless, in order to effectively utilizing these materials for these applications, characterization of their microscopic structure become indispensable. Anyone who has been asked to examine carbon nanotubes in the transmission electron microscopy knows that cylindrical symmetry can be a wonderful thing. For example, it provides information about how many graphene sheets make up a given tube and whether or not the tube has internal terminations. In this presentation, we discuss the projected thickness and diffraction functions that provide a baseline for examining a variety of intensity profiles across nanotube image. These assume that to a first order the tube is cylindrically symmetric, the beam encounters the tube perpendicular to its symmetry axis, and that the contrast mechanisms are simple. The carbon nanotubes (both single- and multi-walled) used in the present study were grown using microwave chemical vapor deposition technique involving acetylene/ammonia gas mixture and iron as catalyst. First, consider darkfield images of a nanotube using the tube layering (e.g. graphite (002)) reflection. As a function of projected radial distance from the tube center, geometry shows this diffraction thickness, d ~ 2r*tan(alpha), where alpha is the fringe visibility half angle for the layer spacing provided the diffracting region is not being truncated by the outer or inner nanotube radii . Secondly, consider the projected thickness, t, of a nanotube of outside radius rmax and inside radius rmin. This looks like for r > rmin, from which you subtract for smaller r. This function has a jump ratio t[rmin] / t, which for a given rmax goes up rapidly in discrete steps to a maximum for single walled tubes. This feature has been helpful in identifying portions of single walled tubes whose outer edges are obscured, although it should be carefully compared to defocus simulations for more quantitative work. Lastly, application for the diffraction and thickness functions above also arises in the study of inelastic mean-free-path images. Mean-free-path “thickness” images can be calculated using the ratios of bright-field and elastic images taken with an energy-filtered TEM. To explore effects of (002) diffraction on inelastic mean-free-path, we profiled such “thickness” images of a bamboo nanotube . In principle, the jump ratio should be sensitive to changes in mean free path, in the (002) diffracting regions, and thus this type of analysis can put upper limits on the size of such effects.  P. Fraundorf et. al. J. Appl. Phys. 98 114308 (2005).  Wang, Gupta et. al. J. Appl. Phys. 97 (2005). Supported by internal Funds.
9:00 PM - KK7.15
Selective Synthesis of Carbon Nanocoil by the Decomposition of Ethylene Using Oxidized-Diamond-Supported Palladium Catalyst.
Mayuko Kikuchi 1 , Kiyoharu Nakagawa 2 , Hidenori Gamo 3 , Toshihiro Ando 4 , Mikka Nishitani-Gamo 1 2 Show Abstract
1 Applied Chemistry, Toyo university, Saitama Japan, 2 Sensor Photonics Research Center, Toyo university, Saitama Japan, 3 Technical Research Institute, Toppan Printing Co.Ltd., Saitama Japan, 4 , National Institute for Materials Science(NIMS), Ibaraki Japan
9:00 PM - KK7.16
The Effect of Excess Carbon on the Crystallographic, Microstructural, and Mechanical Properties of CVD Silicon Carbide Fibers.
James Marzik 1 , William Croft 2 , Warren MoberlyChan 3 Show Abstract
1 , Specialty Materials, Inc., Lowell, Massachusetts, United States, 2 , Harvard University, Cambridge, Massachusetts, United States, 3 , Lawrence Livermore National Laboratory, Livermore, California, United States
9:00 PM - KK7.2
3D e-RAM (Electron Roughness Analyzing Microscope) – an E-Beam System Specifically Developed for Surface Roughness Analysis.
Gary Brake 1 , Yusuke Uchiyama 2 Show Abstract
1 , SEMTech Solutions, North Billerica, Massachusetts, United States, 2 , Elionix, Inc., Tokyo Japan
Scanning Electron Microscopes (SEMs) are widely used for surface observation and elemental analysis in fields that span from R&D to quality control. Naturally, this capability to observe and analyze such surfaces inevitably spurs further curiosity about the topography and roughness of the specimen. To address these inclinations, Elionix has developed the e-RAM, a system that facilitates a 3D measurement of the surface topography and roughness.The greatest advantage of the 3D Electron Roughness Analyzing Microscope over ordinary SEMs is the e-RAM has 4 secondary electron detectors. This 4-channel secondary electron detection system enables quantitative surface roughness measurements and enhances the topography by displaying the differential signal calculated from the 4 signals. The intensities of the detected signals are determined by the tilt angle of the specimen surface in relation to the geometric positioning of the 4 detectors. Thus the SE signal emitted, as described in Lambert's cosine law, can be detected with its angular dependency intact. The quantitative angular information can be obtained by the subtraction between the signal intensities of the detectors. By calculating 4 tilting angles (two in X-direction and two in Y-direction) on many spots in the X-Y matrix taken on the specimen, the surface topography of the specimen can be accurately re-constructed by integrating these angles over the matrix.In the case of an ordinary SEM, which has only one secondary electron detector, the radially emitted secondary electron loses its intrinsic angular information about the specimen surface when it is accelerated and collected by the detector. The resulting brightness in the SEM image is modulated according to the total SE emission, which does not precisely represent the surface topography. Also, given the fact that SEMs have a large depth of focus, it is not uncommon to find difficult instances in which the real topography of the specimen surface is indeterminable. This is especially true for specimens with subtle texture or waviness, whose topography is very difficult to determine even when being tilted. Observation of such samples becomes time-consuming and requires highly-developed skills. Usually, to grasp the topographic information, the specimen needs to be tilted to enhance the topographic contrast of the SEM image. However, tilting of the specimen inevitably causes defocusing, which in turn necessitates dynamic focusing; a process that requires extremely complicated operation. On top of that, tilting the specimen causes discrepancies between the magnification indicated by the micron bar and the actual magnification of the image. The Elionix e-RAM, being equipped with 4 detectors, does not require tilting of the specimen to observe the topography: by simply clicking the mouse, it can switch from the usual SE image to the topographic image, which allows for easy 3D observation and quantitative surface roughness measurements.
9:00 PM - KK7.3
Nano-Hetero Interfaces in Au/TiC Catalysts Characterized by HREM and Electron Holography.
Satoshi Ichikawa 1 , Seiji Takeda 2 , Tomoki Akita 3 , Koji Tanaka 3 , Masanori Kohyama 3 Show Abstract
1 Organization for the Promotion of Research on Nanoscience and Nanotechnology, Osaka University, Toyonaka, Osaka, Japan, 2 Department of Physics, Graduate School of Science, Osaka University, Toyonaka, Osaka, Japan, 3 Research Institute for Ubiquitous Energy Devices, National Institute of Advanced Industrial Science and Technology (AIST), Ikeda, Osaka, Japan
9:00 PM - KK7.4
Comparison of Common Segmentation Techniques Applied to Transmission Electron Microscopy Images.
Thomas Sadowski 1 2 , Christine Broadbridge 1 , John Daponte 2 , Ann Lehman 1 , Lisa Marinella 2 , Paidemwoyo Munhutu 2 , Monica Sawicki 2 Show Abstract
1 Department of Physics, Southern Connecticut State University, Seymour, Connecticut, United States, 2 Department of Computer Science, Southern Connecticut State University, Seymour, Connecticut, United States
Nanoparticles, particles with a diameter of 1-100 nanometers (nm), are of interest in many applications including device fabrication, quantum computing, and sensing because their size may give them properties that are very different from bulk material . Further advancement of nanotechnology cannot be obtained without an increased understanding of nanoparticle properties such as size (diameter) and size distribution frequently evaluated using transmission electron microscopy (TEM) . In the past, these parameters have been obtained from digitized TEM images by manually measuring and counting many of these nanoparticles, a task that is highly subjective. More recently, computer imaging techniques have provided an objective alternative. The first step consists of segmenting a gray scale TEM image into foreground and background regions which is commonly implemented using a thresholding algorithm to produce a binary image. The next step is to perform a particle analysis to count and measure objects in the binary image . Selecting an appropriate thresholding algorithm for image segmentation is complicated by the noisy nature of TEM images and potential contrast issues related to CCD cameras, frequently used to capture these images. The goal of this study was to compare the ability of several popular thresholding algorithms to segment TEM images. The performance of the thresholding algorithms were qualitatively and quantitatively evaluated. Qualitative examination consisted of comparing a gray scale image with the corresponding binary image produced by each thresholding technique. Quantitative measures include region nonuniformity and relative foreground area error . Results show that the choice of a thresholding algorithm will strongly effect the results obtained from particle analysis. This research is partially supported by NSF Grant MRSEC DMR-0520495 and a Connecticut Space Grant NASA EPSCoR Grant.  G. Woehrle, J Hutchison, et. al, J Chem, 20, pp. 1-13, 2006 R. Fisker, J.M. Carstensen, et.al, J Nanoparticle Res., 2 (3), pp. 267-277, 2000 http://rsb.info.nih.gov/ij/index.html M. Sezgin, B. Sankur, J Elec. Image., 13 (10, pp. 146-165, 2004
9:00 PM - KK7.5
In-situ TEM of Colloidal Nanocrystal Growth.
Haimei Zheng 1 , Andrew Minor 1 , Alexander Mastroianni 2 , Paul Alivisatos 2 , Uli Dahmen 1 Show Abstract
1 National Center for Electron Microscopy, Lawrence Berkeley National Laboratory, Berkeley, California, United States, 2 Department of Chemistry, University of California, Berkeley, California, United States
9:00 PM - KK7.6
Interfacial Structure of Epitaxial Pt films on SrTiO3(111) Substrates Identified by HREM and EELS.
Ju-Hyung Suh 1 , Hyung Seok Kim 1 , Chan Gyung Park 1 Show Abstract
1 Materials Science & Engineering, POSTECH, Pohang, Gyeongbuk, Korea (the Republic of)
9:00 PM - KK7.7
Analytical TEM Observations of Au-Pd Nano-particles Prepared by Sonochemical Techniques.
Tomoki Akita 1 , Taiei Hiroki 2 , Shingo Tanaka 1 , Takao Kojima 3 , Fuminobu Hori 2 , Masanori Kohyama 1 , Akihiro Iwase 2 Show Abstract
1 Research Institute for Ubiquitous Energy Devices, National Institute of Advanced Industrial Science and Technology, Ikeda, Osaka, Japan, 2 Department of Materials Science, Osaka Prefecture University, Sakai, Osaka, Japan, 3 Radiation Research Center, Osaka Prefecture University, Sakai, Osaka, Japan
9:00 PM - KK7.8
Strain Characteristics of Self-Assembled InAs/GaAs Quantum Dots Investigated by HR-TEM.
Hyung Seok Kim 1 , Ju Hyung Suh 1 , Chan Gyung Park 1 , Sang Jun Lee 2 , Sam Kyu Noh 2 Show Abstract
1 Mat. Sci. & Eng., POSTECH, Pohang, Kyungbuk, Korea (the Republic of), 2 , Korea Institute of Standards and Science, Daejeon Korea (the Republic of)
T. John Balk University of Kentucky
Andrew Minor Lawrence Berkeley National Laboratory
Alexandra Porter Cambridge University
Juergen Plitzko Max-Planck-Institute of Biochemistry
KK8: Computational Methods in TEM Analysis
Thursday AM, November 30, 2006
Fairfax A (Sheraton)
10:00 AM - **KK8.1
Combining ab initio Density Functional Theory and Transmission Electron Microscopy.
Gerd Duscher 1 2 Show Abstract
1 Materials Science and Engineering, North Carolina State University, Raleigh, North Carolina, United States, 2 Materials Science & Technology, Oak Ridge National Laboratry, Oak Ridge, Tennessee, United States
10:30 AM - KK8.2
Compositional Analysis of III-V Semiconductor Interfaces Using Exit-Plane Wave Retrieval in High-Resolution Transmission Electron Microscopy.
Krishnamurthy Mahalingam 1 , Kurt Eyink 1 , Gail Brown 1 , Donald Dorsey 1 Show Abstract
1 , Air Force Research Laboratory, Wright-Patterson AFB, Ohio, United States
Existing techniques based on high-resolution transmission electron microscopy (HRTEM) for compositional analysis of III-V semiconductor interfaces are restricted to ternary systems (i.e. intermixing in either the group-III or group-V sublattice). They further require images obtained under optimum specimen-thickness and imaging conditions, which depend on the system being investigated. In this work we have developed an approach, employing exit-plane wave function (EPWF) retrieval from conventional HRTEM images, which enables atomic-scale quantitative chemical analysis of quaternary III-V semiconductor interfaces with intermixing in both group-III and group-V sublattices. Specifically, using the focal series reconstruction technique for EPWF retrieval in combination with multivariate statistical analysis we show that compositional profiles along the group-III and group-V sublattices can be independently extracted. We have applied this approach for determining the stoichiometry of interfaces in heterostructures based on the InAs-GaSb system. Analysis of the In-Ga and the As-Sb contents across interfacial regions ≈ 0.6 nm wide in an InGaSb-InAs heterostructure, revealed that disorder at the InGaSb-on-InAs interface was confined to the In-Ga sublattice. In addition, atomic-scale roughness was discerned within the As-Sb sublattice of the InAs-on-InGaSb interface. This approach is general, permitting atomic scale analysis of interfaces with up to two species per sublattice. Further studies on short-period InAs-GaSb superlattices (individual layer thickness ranging from 1-3 nm) with nominal and precisely tailored interfaces will be presented.
10:45 AM - KK8.3
Atomic Structure and Dynamics of Nanocatalysts by Aberration-Corrected STEM and Theory.
Albina Borisevich 1 , Sergey Rashkeev 1 2 , Ryszard Buczko 3 , Sanwu Wang 2 , Sokrates Pantelides 2 1 , Stephen Pennycook 1 2 Show Abstract
1 , ORNL, Oak Ridge , Tennessee, United States, 2 , Vanderbilt University, Nashville, Tennessee, United States, 3 , Institute of Physics, Polish Academy of Sciences, Warsaw Poland
11:30 AM - **KK8.4
Computational Tools for Interpreting Biological Electron Tomograms.
Niels Volkmann 1 Show Abstract
1 Bioinformatics & Systems Biology Department, Burnham Institute for Medical Research, La Jolla, California, United States
12:00 PM - KK8.5
Determining Nanoscale Order in Amorphous Materials: Simulations of Fluctuation Electron Microscopy for Amorphous Si.
Stephanie Bogle 1 , Paul Voyles 2 , John Abelson 1 Show Abstract
1 Department of Materials Science & Engineering and the Materials Research Laboratory, University of Illinois at Urbana-Champaign, Urbana, Illinois, United States, 2 Department of Materials Science & Engineering, University of Wisconsin-Madison, Madison, Wisconsin, United States
12:15 PM - KK8.6
Advanced Computerized Analysis of Pt-Nanoparticles on Glassy Carbon using Transmission Electron Microscopy Data.
Petra Bele 1 , Franziska Jäger 1 , Ulrich Stimming 1 Show Abstract
1 Department of Physics E19, Technical University Munich, Garching Germany
For the determination of a model catalyst system by means of particle size and size distribution TEM is a state-of-the art method. Here we like to present a data analysis using an advanced computer image processing routine applied to a novel Pt-catalyst system on glassy carbon. The analysis enables us to achieve statistically meaningful data.Due to the fact that nanoparticles with a particle size above 4 nm do not show significant size effects  it is essential to prepare particles smaller than 4 to 5 nm. Also it demands supplementary a very narrow size distribution to achieve a thorough investigation of a model catalyst system.With our novel approach [1,2] to vary the size of Pt-nanoparticles supported on glassy carbon we are able to accomplish both of these requirements. The combination of the electrochemical and the chemical deposition enables the preparation of particles in the interval of ~1 – 5 nm and with a very narrow size distribution. This leads to the problem of the significant characterization of particles in the sub-nanometer scale. Major disadvantages of the conventional bright-field TEM are the variation of image contrast between adjacent particles, by overlapping of multiple particles and the difficulty to distinguish sub-nanometer particles from the matrix. Also it is well known that there are some difficulties using computer-assisted image analysis in the sub-nanometer range .To avoid all these obstacles we used an advanced computerized image processing procedure to evaluate the particle size and size distribution of our new model catalyst. Enough images were taken to be as representative as possible of the bulk sample and to obtain a statistically sufficient number of counted particles. First the standard image processing using background correction and contrast enhancement we performed. For the final determination of the particle diameter we used an adaptive local thresholding instead of the normally applied global threshold. This local threshold is adjusted to the different parts of the image and is the key for a fast determination even for particles with a diameter smaller than 1 nm.To cross-check our results high-angle annular dark-field (HAADF) measurements were performed and the images were processed in the same way as the bright-field images.Our results clearly show that the advanced image processing using a local threshold establish a fast and easy way to get the particle size analysis done even in the sub-nanometer range.References F. Maillard, M. Eikerling, O. V. Cherstiouk, S. Schreier, E. Savinova, U. Stimming, Faraday Discuss.125 (2004) 357 F. Jäger, Ph.D. thesis 2006 M.T. Reetz, M. Maase, T. Schilling, B. Tesche, J. Phys. Chem. B 104 (2000) 8779-8781
12:30 PM - **KK8.7
Diffraction Limited Atomic Resolution Imaging of Noncrystalline, Molecular, Structures.
Jian-Min Zuo 1 Show Abstract
1 Materials Science, Univ. Illinois, Urbana, Urbana, Illinois, United States
KK9: TEM for Properties Analysis
Thursday PM, November 30, 2006
Fairfax A (Sheraton)
2:30 PM - KK9.1
TEM Investigation of the Deformation Mechanism in Nanocrystalline Tantalum.
Yinmin (Morris) Wang 1 , Andrea Hodge 1 , Troy Barbee 1 , Alex Hamza 1 Show Abstract
1 Chemistry and Materials Science Directorate, Lawrence Livermore National Laboratory, Livermore, California, United States
2:45 PM - KK9.2
Free-standing Graphene Membranes.
Jannik Meyer 1 , Andre Geim 2 , Kostya Novoselov 2 , Tim Booth 2 , Mikhail Katsnelson 3 , Siegmar Roth 1 Show Abstract
1 , Max-Planck Institute for solid state research, Stuttgart Germany, 2 Manchester Centre for Mesoscience and Nanotechnology, University of Manchester, Manchester United Kingdom, 3 Institute for Molecules and Materials , University of Nijmegen, Nijmegen Netherlands
3:00 PM - **KK9.3
Magnetic Properties, Microstructure, Composition and Morphology of Ferrimagnetic Nanocrystals in Magnetotactic Bacteria from Electron Holography and Tomography.
Rafal Dunin-Borkowski 1 2 , Takeshi Kasama 2 1 , Mihaly Posfai 3 , Ryan Chong 1 , Richard Frankel 4 Show Abstract
1 Department of Materials Science and Metallurgy, University of Cambridge, Cambridge United Kingdom, 2 Frontier Research System, The Institute of Physical and Chemical Research, Wako Japan, 3 Department of Earth and Environmental Sciences, Pannon University, Veszprem Hungary, 4 Department of Physics, California Polytechnic State University, San Luis Obispo, California, United States
3:30 PM - KK9.4
Octahedral-tilt-transition and Defect Ordering in SrTi0.95Mn0.05O3−δ Ceramics.
Paula Vilarinho 1 , Alexander Tkach 1 , Ian Reaney 2 , Andrei Kholkin 1 Show Abstract
1 Ceramics and Glass Engineering, University of Aveiro, Aveiro Portugal, 2 Department of Engineering Materials, University of Sheffield, Sheffield United Kingdom
3:45 PM - KK9.5
Microstructure Evolution in Deformed Copper and Nickel.
Peri Landau 1 , Roni Shneck 1 , Guy Makov 2 , Arie Venkert 2 Show Abstract
1 Materials Engineering, Ben-Gurion University, Beer Sheva Israel, 2 Physics, NRCN, Beer Sheva Israel
Dislocation patterning in fcc metals following plastic deformation has been extensively investigated using transmission electron microscopy. Although the microstructural features following plastic deformation are similar, there are still noticeable differences between metals having different stacking fault energy (SFE). Deformed aluminum, nickel and copper form similar dislocation patterns, for example: dislocation cells, dense dislocation walls and incidental dislocation boundaries. Nevertheless, the arrangement of dislocations into different patterns varies for each metal. In this work the combined effect of strain and temperature on compressed copper and nickel was systematically studied and is presented in microstructural maps. A comparison between the different microstructures observed is discussed. Furthermore, a comparison between the detailed structures of dislocation boundaries (DBs) is presented. Copper forms two distinct dislocation patterns: dislocation cells and second generation microbands (MBs). With increasing strain and temperature the dominance of the MBs is evident and at the highest temperatures only MBs are formed. Nickel forms a cellular structure and MBs are not observed. With increasing temperature a subgrain structure is formed, combined with sparse dislocation walls. The preferred dislocation pattern is determined by the dislocation mobility and opportunity to cross slip. The differences in the deformed microstructure are attributed to the differences in the SFE (Nickel has a higher SFE compared to copper). Copper, which has a relatively low mobility of dislocations and lower opportunity to cross slip, forms MBs to relieve local shear. Nickel forms dislocation cells and subgrains following plastic deformation, similar to those observed in aluminum. Looking into the detailed structure of DBs, it seems that dislocations prefer to order into arrays of parallel dislocations, given sufficient mobility and strain. Nickel requires strain in order to form piecewise arrays because of the high mobility and opportunity to cross slip, similar to aluminum. Copper requires higher strains or a combination of strain and temperature.
4:00 PM - KK9.6
Characterization of Stress Relaxation in a Strained Si Film by Geometric Phase Analysis.
Jayhoon Chung 2 , Lew Rabenberg 1 Show Abstract
2 , Texas Instruments, Dallas, Texas, United States, 1 Material Science and Engineering, University of Texas at Austin, Austin, Texas, United States