Suneel Kodambaka University of California-Los Angeles
Guus Rijnders University of Twente
Amanda Petford-Long Argonne National Laboratory
Andrew Minor Lawrence Berkeley National Laboratory
Stig Helveg Haldor Topsoe A/S
Alexander Ziegler Max-Planck Institute for Biochemistry
NN1/EE1: Joint Session: In-situ Nanomechanics
Monday PM, December 01, 2008
Room 200 (Hynes)
9:00 AM - NN1.1/EE1.1
SEM In situ Compression of Silicon Nanowires.
William Mook 1 , Rudy Ghisleni 1 , Karolina Rzepiejewska-Malyska 1 , Samuel Hoffmann 1 , Laetitia Philippe 1 , Johann Michler 1 Show Abstract
1 , Swiss Federal Laboratories for Materials Testing and Research (EMPA), Thun Switzerland
Silicon nanowires have created a great deal of interest for over a decade due to their enhanced electrical properties when compared to bulk values. These structures also show size-dependent mechanical properties and since they can determine the reliability of many nanodevices and nanosystems, it necessary to quantify their elastic and plastic mechanical response to externally applied loads. This, however, is experimentally challenging due to the length scales involved. Therefore uniaxial compression experiments have been performed in situ with a high resolution scanning electron microscope (SEM) on single crystal silicon nanowires with diameters ranging from 100 nm to 1 μm. A flat-punch indenter can be positioned above the structure of interest with nanometer precision without modifying it due to deformation from mechanical scanning. Compressions are then run under displacement-control at 1 nm/s. By observing the deformation and contact area throughout the experiment engineering stress-strain curves can be extracted from the load-displacement data. Nanowire compressive strength is compared to silicon micropillar compression experiments and to silicon wires in bending.
9:15 AM - NN1.2/EE1.2
SEM In situ Micropillar Compression - Room Temperature Ductile to Brittle Transition of Si, GaAs, InP Semiconductors.
Johann Michler 1 , Fredrik Oestlund 1 , Karolina Rzepiejewska-Malyska 1 , William Mook 1 , Klaus Leifer 2 , Rudy Ghisleni 1 Show Abstract
1 , Swiss Federal Laboratories for Materials Testing and Research (EMPA), Thun Switzerland, 2 Electron Microscopy and Nanoengineering, Department of Engineering Science, Uppsala University, Uppsala Sweden
Current fabrication technology is capable of producing micro- to nano-meter scale structures. The mechanical response of such structures has been shown to depend upon length scales such as pillar diameter. These findings contradict the classical laws of mechanics which assume that mechanical properties are independent of sample size. This contradiction has fostered an increasing number of investigations into mechanical size effects in order to accurately design and fabricate devices at these scales. In an effort to characterize and understand the mechanical behaviour dependence on the size, an investigation on single crystal semiconductor micropillars is presented. Single crystal silicon, gallium arsenide, and indium phosphide micropillars were fabricated by a focused ion beam (FIB) technique. The diameter of the pillars ranged from 200 nm to 10 μm with a length to diameter aspect ratio of three. The micropillars’ mechanical response was investigated by uniaxial compression tests performed with a diamond flat punch using an in situ SEM nanoindenter instrument.Engineering stress-strain curves as a function of pillar diameter are presented. The results show that all the investigated semiconductor materials exhibited a brittle to ductile transition with a decrease in pillar diameter. The deformation mechanism that is responsible for the plasticity is shown to be the formation of Shockley partial dislocations. The decrease of the projected pillar diameter on the crystal slip plane below the equilibrium distance (proportional to the stacking fault energy) between the leading and trailing partial dislocation controls the transition from a brittle to ductile behavior.
9:30 AM - NN1.3/EE1.3
In-situ Investigation of Nano-scale Plasticity in Cubic and Tetragonal Crystals via Homogeneous Deformation of Nano-Pillars.
Julia Greer 1 , Ju-Young Kim 1 , Steffen Brinckmann 1 Show Abstract
1 Materials Science, California Institute of Technology, Pasadena, California, United States
Strength of crystalline materials at reduced dimensions is important for fabrication and reliability of devices at nanometer scales such as MEMS and NEMS, bio-cell sensors, and fuel cells. Plastic flow stress of crystals, a size-independent property for bulk, is found to strongly depend on sample size as it is reduced to nano-scale. To investigate plasticity under homogeneous deformation, we have developed an in-situ micro-deformation methodology, where nano-pillars are mechanically deformed in a one-of-a-kind instrument, SEMentor, which merges the strengths of SEM and Nanoindenter, and offers the advantage of measuring mechanical response of nano-scale materials while capturing video frames throughout the deformation process. We present for the first time results of compression and tension tests performed in-situ inside SEMentor, where load-displacement data is correlated with real-time slip step formation on the surface of the deforming specimens. We perform a new robust technique for stress-strain calculation based on load-displacement data. We also report mechanical strengths of uniaxially-deformed single crystalline nano-pillars with different crystallographic structures (Au, Al, In, Mo) and compare them with one another. Our experiments demonstrate pronounced differences in the behavior of individual structures, and possibly plasticity mechanisms are discussed. We find that although all crystals show an increase in flow stress with decreasing diameter in a power-law fashion, the slopes of these size effects vary with the material, and the ratio between the observed maximum flow stress and the theoretical strength vary significantly.
9:45 AM - NN1.4/EE1.4
Quantitative In Situ Tensile Testing of 1D Nanostructures.
Daniel Gianola 1 , Reiner Moenig 1 , Oliver Kraft 1 2 , Cynthia Volkert 3 Show Abstract
1 Institute for Materials Research II, Forschungszentrum Karlsruhe, Karlsruhe Germany, 2 , University of Karlsruhe, Karlsruhe Germany, 3 Institut für Materialphysik, Universität Göttingen, Göttingen Germany
Plasticity in extremely small volumes is fundamentally different than in large materials; the law of averages gives way to discrete processes that dominate the response. Probing the mechanical response and uncovering the underlying deformation mechanisms of diminishingly small structures at the micro- and nanoscale requires new strategies and approaches that circumvent difficulties associated with handling, gripping, loading, and measuring small specimens. The need for in situ experiments that give a one-to-one correlation between mechanical response and deformation morphology is exacerbated by the fact that electron optics are needed to image and manipulate nanostructures. Tensile experiments are the preferred modality at larger scales since they apply a homogeneous stress state and are less sensitive to boundary conditions, easing interpretation. Meanwhile, results obtained using the popularly employed techniques at the nanoscale (e.g. nanoindentation, micro-compression testing) are clouded by these unresolved issues. Here we describe quantitative in situ tensile experiments on 1D nanostructures in a dual-beam scanning electron microscope (SEM) and focused ion beam (FIB). Specimen manipulation, transfer, and alignment are performed using an in situ manipulator, independently-controlled positioners, and the FIB. Gripping of specimens is achieved using electron-beam assisted Pt deposition. Local strain measurements are obtained using digital image correlation of SEM images taken during testing. Examples showing results for single-crystalline metallic nanowires and nanowhiskers, having diameters between 30 and 300 nm, will be presented in the context of size effects on mechanical behavior, the theoretical strength of crystals, and the influence of defects on the accommodation of plasticity in small volumes.
10:00 AM - **NN1.5/EE1.5
Observation of Size-Dependent Plasticity by In Situ SEM and TEM.
Gerhard Dehm 1 2 Show Abstract
1 Erich Schmid Institute of Materials Science, Austrian Academy of Sciences, Leoben Austria, 2 Materials Physics, University of Leoben, Leoben Austria
The continuing trend of miniaturizing materials in many modern technological applications has led to a strong demand for understanding the complex mechanical properties of materials at small length scales. This talk focuses on the recent understanding of the size-dependent plasticity in face-centered cubic metals with dimensions of several microns down to some tens of nanometers. At that length scale sophisticated measurement approaches are required with the advantage of in situ microscopy techniques providing both, control of the deformation experiment and insight in the underlying deformation mechanisms. Size effects of the flow stresses are compared for “wires” and thin films on compliant or stiff substrates. The interpretation of the results is based on recent insights on dislocation nucleation, glide band formation, and dislocation mobility stemming from in-situ SEM and TEM studies of single-crystalline and polycrystalline samples. The results are discussed with the attempt to explain the size effects in straining experiments at small length scales.Acknowledgement: Significant contributions from D. Kiener, R. Pippan, S.H. Oh (Leoben), M. Legros (Toulouse), and P. Gruber (Stuttgart) are acknowledged.
11:00 AM - NN1.6/EE1.6
In Situ Examination of Nanoscale Deformation of Thin Film Bridges within a Scanning Electron Microscope.
Erik Herbert 1 , Arnold Lumsdaine 1 , R. Brian Peters 1 , Warren Oliver 1 Show Abstract
1 , Agilent Technologies, Oak Ridge, Tennessee, United States
Using a high precision nanoindentation head, a new technique has recently been developed to determine the elastic modulus and residual stress of a free-standing doubly-clamped thin film bridge . A desire to examine the impact of certain anomalies in the experimental results (possibly occurring due to misalignment of the tip of the nanoindentation head with the surface of the bridge or due to adhesion of the tip with the surface of the bridge) motivates an examination of the experiment within a scanning electron microscope (SEM). A linear feedthrough mechanism has been developed to position the indentation head within the SEM chamber for precise targeting of the thin film bridge sample (placed on the SEM sample stage). This configuration also allows for the examination of the multi-dimensional deformation state of the bridge when the indentation head contact occurs offset from the center of the bridge.E.G. Herbert, W.C. Oliver, M. P. de Boer, and G.M. Pharr, “Measuring the Elastic Modulus and Residual Stress of Free-Standing Thin Film Bridges by Nanoindentation,” 2007 MRS Spring Meeting, 2007.
11:15 AM - **NN1.7/EE1.7
A New Perspective on Nano-Mechanics: Quantitative Deformation Test in the TEM
Zhiwei Shan 1 , A. Minor 2 3 , J. Nowak 1 , S. Syed Asif 1 , O. Warren 1 Show Abstract
1 , Hysitron Inc., Eden Prairie, Minnesota, United States, 2 , Lawrence Berkeley National Laboratory, Berkeley, California, United States, 3 , University of California , Berkeley, California, United States
It is often a challenge to measure accurately the mechanical properties of nanostructures and nanomaterials on account of their extremely small physical dimensions. Recently, we have developed an in situ TEM nanomechanical testing apparatus. This device enables one to acquire quantitative mechanical data while simultaneously recording the microstructural evolution of the materials during deformation, developing a one-to-one relationship between an imposed stress and an individual deformation event. In this talk, we report on the current progress in the application of this in situ TEM device for measuring the mechanical behavior of individual single crystal nickel and metallic glass (MG) pillars. Prior to the deformation tests, the Focused Ion Beam (FIB) fabricated nickel pillars were observed to contain a high density of defects. However, quite unexpectedly, the defects density was observed to decrease dramatically during the deformation process and, in some cases, even resulted in a dislocation-free crystal. The phenomena which we termed as “mechanical annealing” is the first direct observation of the dislocation starvation mechanism and sheds new light on the unusual mechanical properties associated with submicron- and nano- scale structures (Shan et al, Nature Materials, 2008). The compression tests on Cu-Zr-Al MG pillars revealed the intrinsic ability of fully glassy MGs to sustain large plastic strains, which would otherwise be preempted by catastrophic instability in macroscopic samples and conventional tests (Shan et al, PRB, 2008).
11:45 AM - NN1.8/EE1.8
In- Situ Observation of Deformation Characteristics in Nanotwinned Copper Pillars.
Vinay Sriram 1 , Jia Ye 2 3 , Andrew Minor 2 3 , Jenn-Ming Yang 1 Show Abstract
1 Department of Materials Science and Engineering, University of California Los Angeles, Los Angeles, California, United States, 2 National Centre for Electron Microscopy, Lawrence Berkeley National Lab, Berkeley, California, United States, 3 Department of Materials Science and Engineering, University of California Berkeley, Berkeley, California, United States
The semiconductor industry is currently moving towards integration of “air gap” technology beyond the 32nm node. A major concern in the introduction of air gap technology is the mechanical integrity, reliability and stability of the vias and interconnects line structures. A new method based on In-situ Transmission Electron Microscopy nanocompression testing of copper pillars which are of the same size scale of vias, interconnects will be presented. Copper pillars having nanotwined boundaries and nanocrystalline grains were tested by this technique. We show direct evidence that twin boundaries can withstand extensive plastic deformation and still retain their structure when compared to regular grain boundaries. The deformation mechanisms of twin boundaries predicted by Molecular Dynamic (MD) simulations has been verified by real-time TEM analysis. Quantitative in-situ stress measurements for deformation twinning are in close agreement with those reported by first principle based calculations.
12:00 PM - NN1.9/EE1.9
In Situ TEM Nanocompression Testing of Gum Metal.
Elizabeth Withey 1 , Andrew Minor 2 , Jia Ye 2 , Shigeru Kuramoto 3 , Daryl Chrzan 1 , John Morris 1 Show Abstract
1 Materials Science and Engineering, University of California, Berkeley, Berkeley, California, United States, 2 , National Center for Electron Microscopy, Lawrence Berkeley National Laboratory, Berkeley, California, United States, 3 , Toyota Central R&D Laboratories, Inc., Nagakute Japan
“Gum Metal” is a newly developed β-Ti alloy that, in the cold-worked condition, has exceptional elastic elongation and high strength. The available evidence suggests that Gum Metal does not yield until the applied stress approaches the ideal strength, and then deforms by mechanisms that do not involve conventional dislocation plasticity. To study its behavior, submicron-sized pillars of solution-treated and cold-worked Gum Metal were compressed in situ in a quantitative compression stage in a transmission electron microscope. Quantitative load vs. displacement data was correlated to real-time images to determine a pattern of deformation that agrees with previous results from ex situ nanoindentation.
12:15 PM - NN1.10/EE1.10
Thermal Behavior of Gold Nanoparticles on Pyrite and Arsenopyrite Surfaces.
Niravun Pavenayotin 1 , Qiangmin Wei 2 , Yanbin Chen 1 , Lumin Wang 1 2 Show Abstract
1 Nuclear Engineering and Radiological Sciences, University of Michigan, Ann Arbor, Michigan, United States, 2 Materials Science and Engineering, University of Michigan, Ann Arbor, Michigan, United States
Diffusion of gold nanoparticle on pyrite (FeS2) and arsenopyrite (FeAsS) surfaces was studied under in-situ TEM. The gold nanoparticles were deposited onto the surfaces by sputtering of gold TEM grids by ion milling. The gold nanoparticles have a uniform size of approximately 2 nm in diameter. The samples were heated up using a hot stage in the TEM to 100, 200, 300, 400, 500 and 550°C. The movement and characteristics of the nanoparticles were monitored by in situ TEM. The gold nanoparticles coalesce and grow by Oswald’s ripening as the temperature rises. At 500°C, pyrite starts to decompose into amorphous Fe and S. Gold particles on the decomposed surface are driven together and form particles as large as 30 nm in diameter while at the same temperature the gold particles in arsenopyrite are less than 20nm in diameter. Some of the solid gold nanoparticles on pyrite surface also melt and form a film-like morphology. Arsenopyrite does not decompose until 550°C. The gold particles that reside on top of the amorphous decomposed region are immobile. The particles on the crystalline surface grow at a fast rate and visibly mobile on the surface. The differences in the diffusion behavior of gold nanoparticles on two different pyrites will be explained.
12:30 PM - **NN1.11/EE1.11
Revealing the Deformation Processes Responsible for Controlling Mechanical Properties.
Ian Robertson 1 Show Abstract
1 Materials Science and Engineering, University of Illinois, Urbana, Illinois, United States
Transmission electron microscopes have played a critical role in building our knowledge base regarding dislocations, dislocation-obstacle interactions and microstructural evolution as a function of deformation history. Past usage yielded primarily snapshots of the microstructure, leaving the pathways by which it was attained to be deduced. Development of straining stages for use in electron microscopes, cameras for capturing the reaction dynamics and computer technology and software for image processing have enabled observation of dislocation processes in real time and at the spatial resolution of the instrument. Provided the impact of the thin film geometry and the stress state are appreciated, this technique can and has been used to provide visual and quantitative information about dislocation reactions and processes. The results of these studies are now being incorporated into physically-based models for predicting the mechanical properties. Recent developments in stage design provide the capability to measure the macroscopic response and to simultaneously observe the deformation behavior, thus, providing the opportunity to correlate microscopic processes with a macroscopic property. In this talk, examples of applications of standard and new straining stages will be used to illustrate how these tools have advanced our understanding of dislocation reactions and processes and how this insight has been used to yield new models.
NN2: In-situ Growth and Characterization of Nanotubes
Monday PM, December 01, 2008
Room 102 (Hynes)
2:30 PM - **NN2.1
In-Situ Electrical, Mechanical, and Thermal Properties of Carbon Nanotubes and Nanowires by using a TEM-SPM Platform.
Jianyu Huang 1 Show Abstract
1 Center for Integrated Nanotechnologies (CINT), Sandia National Laboratories, Albuquerque, New Mexico, United States
In this talk, I will review our recent progress in using a transmission electron microscopy – scanning probe microscopy (TEM-SPM) platform to probe in-situ the electrical, mechanical and thermal properties of carbon nanotubes  and nanowires. First, buckyballs are formed inside the hollow of multiwall carbon nanotubes, and the buckyballs shrink continuously until they disintegrate, proving the “shrink-wrap” buckyball formation mechanism. Second, using carbon nanotubes as heaters and carbon onions as high-pressure cells, a temperature higher than 2000 °C and a pressure higher than 40 GPa are created in the core of the carbon onions. At such a high pressure and a high temperature, the diamond formed in the carbon onion core exhibits a quasimelting state. Third, plastic deformation, such as superplasticity, kink motion, dislocation climb, and vacancy migration, is discovered in nanotubes. Fourth, nanowires are elongated to a record length without any dislocation activity. Finally, in-situ thermal measurement will be highlighted. J.Y. Huang et al., Nature 439, 281 (2006); J.Y. Huang et al., Phys. Rev. Lett. 94, 236802 (2005); 97, 075501 (2006); 98, 185501 (2007); 99, 175593 (2007); 100, 035503 (2008).
3:00 PM - **NN2.2
Frontiers of In-situ TEM: Thermal Imaging of Nanotubes and Lorentz Imaging of Nanomagnetic Lattices.
John Cumings 1 , Todd Brintlinger 1 , Yi Qi 1 , Kamal Baloch 1 2 Show Abstract
1 Department of Materials Science and Engineering, University of Maryland, College Park, Maryland, United States, 2 Institute for Physical Science and Technology, University of Maryland, College Park, Maryland, United States
In-situ transmission electron microscopy is a rapidly-growing field with many frontiers of research. Most commonly, in-situ techniques are used to study the processing or growth of novel materials. In a different and expanding area of research, in-situ techniques are used instead for uncovering the properties of operational devices and dynamic systems. One example of this is carbon nanotubes under thermal transport conditions. To study this, we have developed a novel thermal imaging technique, electron thermal microscopy , and I will present results applying this technique to the thermal transport of carbon nanotubes. Another growing area of research is the study of interactions of magnetic elements structured at the nanoscale. In one groundbreaking avenue , interacting magnetic elements are patterned on periodic lattices that prevent long-range order. Such systems are frustrated and have the potential for revealing fundamental microscopic properties in materials as diverse as rare-earth oxides and ice. Furthermore, they are highly relevant to technologies which desire to pack magnetic information into increasingly smaller areas, such as MRAM and magnetic hard disk drives. I will present results on in-situ TEM studies of these novel artificially frustrated magnetic systems, and will discuss some of the implications for emerging technologies. This work was supported in part by the NSF-MRSEC at the University of Maryland and utilized its shared equipment facilities, under contract DMR 0520471 T. Brintlinger et al., Nano Letters, 8, 582 (2008).  R. F. Wang et al., Nature, 439, 303 (2006).
3:30 PM - NN2.3
Local Electrical Transport Measurements at LaAlO3/SrTiO3 Interfaces Using STM in TEM.
Johan Borjesson 1 , Alexey Kalabukhov 2 , Robert Gunnarsson 2 , Tord Claeson 2 , Dag Winkler 2 , Krister Svensson 3 , Eva Olsson 1 Show Abstract
1 Microscopy&Microanalysis, Chalmers University of Technology, Gothenburg Sweden, 2 Microtechnology and Nanosience, Chalmers University of Technology, Gothenburg Sweden, 3 Physics and Electrical Engineering, Karlstad University, Karlstad Sweden
LaAlO3 (LAO) and SrTiO3 (STO) are insulators but when an epitaxial LAO thin film is deposited on a STO substrate the interface can show electrical conduction. The conductivity is believed to be due to an induced two-dimensional electron gas at the interface and/or oxygen vacancy doping of the STO in the vicinity of the film/substrate interface. The properties of the interface depend on the oxygen pressure during the LAO thin film growth and on the film thickness. In this work the atomic structure of different interfaces has been determined by high resolution analytical transmission electron microscopy (TEM) using a Titan 80-300 with a probe Cs corrector and a monochromator. The local electrical transport properties have been studied using an in-situ scanning tunneling (STM)-TEM holder. This holder allows simultaneous contacting/electrical characterization and imaging by TEM and scanning TEM (STEM). A direct correlation between atomic structure and electrical transport properties is thereby obtained. Information about oxygen vacancies at and in the vicinity of the film/substrate interface is obtained by electron energy loss spectroscopy.
3:45 PM - NN2.4
In-situ and Ex-situ TEM Microscopy and Spectroscopy Studies of Interfaces in Li-ion Battery Materials.
Chongmin Wang 1 , Gary Yang 2 , S. Thevuthasan 1 , J. Liu 3 , D. Baer 1 , L. Saraf 1 , Wu Xu 2 , J. Zhang 2 , D. Wang 3 , N. Salmon 4 Show Abstract
1 Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, Richland, Washington, United States, 2 Energy and Environmental Directorate, Pacific Northwest National Laboratory, Richland, Washington, United States, 3 Fundamental and Computational Science Directorate, Pacific Northwest National Laboratory, Richland, Washington, United States, 4 , Hummingbird Scientific, Lacey, Washington, United States
Electrochemical energy storage devices (EES), such as Li-ion batteries, are complex multi-component systems that incorporate widely dissimilar materials and materials phases in physical and electrical contact. The operation of an EES relies critically on electronic and ionic transference across solid–solid and solid–liquid interfaces and within each of the constituent phases. These interfaces may include a reaction front moving through a particle in a two phase reaction; or an interface between the conducting electrode and the electrolyte. The largest and most critical challenge facing an EES is the basic understanding of the structural evolution within the constituent materials and that across the interface/interphase during the cyclic operation of a cell and the consequence of such structural evolution on the properties and lifetime of the cell. In general, mechanisms associated with the intercalation and deintercalation of Li ions in a Li-ion battery system is not fully understood. The structure of the interface between Li intercalated region and the Li free one and the propagation of this interface during charge and discharge of the battery are not well known. Overall, this imposes a fundamental scientific question as how the microstructures within the constituent materials and across the interface/interphase confined by the constituents evolve and impact the properties of the lithium ion battery. Ex-situ methods based on electron beam imaging and spectroscopy has been widely used for probing the structural features of an EES system. However, due to the dynamic structural nature of the process and the sensitivity of some of the materials to air, the ex-situ method cannot answer some of the questions that are related to the dynamical operation of the EES. In-situ capabilities that enable the observation of the structural and chemical changes during the dynamic operation of a battery are most appropriate for addressing this scientific and technological challenge. We have been developing a Transmission electron microscopy (TEM) holder that allows direct observation of the chemical and structural evolution at the interface between the electrolyte and the electrode as well as within the electrodes under the dynamic operation conditions of the Li ion battery system. We have investigated the structural evolution at the interface between TiO2 nanowire anode and the Li based electrolyte using TEM imaging, electron diffraction, and electron energy-loss spectroscopy (EELS) under the operating conditions a battery.
4:30 PM - **NN2.5
Investigating Catalyst Behavior Prior to and During the Growth of Carbon Nanotubes with Real Time TEM.
Eric Stach 1 , Sueng Min Kim 1 , Dmitri Zakharov 2 , Placidus Amama 4 , Cary Pint 3 , Robert Hauge 3 , Benji Maruyama 5 Show Abstract
1 School of Materials Engineering and Birck Nanotechnology Center, Purdue University, West Lafayette, Indiana, United States, 2 Birck Nanotechnology Center, Purdue University, West Lafayette, Indiana, United States, 4 , Universal Technology Corporation, Dayton, Ohio, United States, 3 Department of Chemistry, Rice University, Houston, Texas, United States, 5 Materials and Manufacturing Direcorate, Wright Patterson Air Force Research Laboratory, Dayton, Ohio, United States
5:00 PM - NN2.6
In-situ Electrical Probing of Silicon During Nanoindentation.
Simon Ruffell 1 , Jim Williams 1 , Jodie Bradby 1 , Naoki Fujisawa 1 , Ryan Major 2 , Oden Warren 2 Show Abstract
1 Electronic Materials Engineering, Australian National University, Canberra, Australian Capital Territory, Australia, 2 , Hysitron Inc., Minneapolis, Minnesota, United States
The Hysitron nanoECR system allows in-situ electrical measurements to be performed during nanoindentation testing. With examples from our work on nanoindentation-induced phase transformations in silicon, we illustrate that the electrical measurements are extremely powerful in aiding understanding of the phase transformation behaviour. They have high sensitivity and can be directly correlated with the mechanical load/unload data.We have shown that under both constant voltage and I-V sweep modes we can track the formation of high pressure crystalline phases (Si-III and Si-XII) during unloading. Careful analysis of through-tip current during constant voltage experiments reveals that the nucleation of these crystalline phases, from the Si-II phase formed during loading, can also be monitored. In addition, the system can be operated as a point probe which has high sensitivity to the local microstructure of phase transformed zones. In particular the I-V characteristics of the tip/sample contact are extremely sensitive to the local material allowing spatial mapping of conductivity within a residual indent. This high sensitivity has allowed detection of seed volumes of these crystalline phases in amorphous Si, that are below detection limits of ex-situ techniques such as Raman micro-spectroscopy. Subtle changes in the final microstructure, which can be modified by changing the starting matrix (i.e. amorphous or crystalline silicon) can also be detected by through-tip conductivity measurements. Finally, we discuss some technical issues related to the capability of making quantitative measurements and show ex-situ electrical measurements which allow correlation of in-situ electrical measurements with electrical properties of the nanoindentation-induced silicon.
5:15 PM - NN2.7
Atomic Scale In-situ Environmental TEM of the Nanoparticle Catalysts for the Nucleation and Growth of Carbon Nanotubes in CVD Condition.
Hideto Yoshida 1 , Tetsuya Uchiyama 1 , Yuusuke Tanemoto 1 , Kazuto Ofuji 1 , Seiji Takeda 1 , Yoshikazu Homma 2 Show Abstract
1 , Osaka Univ., Osaka Japan, 2 , Tokyo University of Science, Tokyo Japan
5:30 PM - NN2.8
In-situ XPS Study of Supported Transition Metal Catalysts during Carbon Nanotube Growth.
Stephan Hofmann 1 , Raoul Blume 2 , Tobias Wirth 1 , Cecilia Mattevi 3 , Cinzia Cepek 3 , Andrea Goldoni 4 , Axel Knop-Gericke 2 , Robert Schloegl 2 , John Robertson 1 Show Abstract
1 Dep. of Engineering, Cambridge University, Cambridge United Kingdom, 2 , Frtiz-Haber Institute, Berlin Germany, 3 , TASC-CNR-INFM, Trieste Italy, 4 , Sincrotrone Trieste SCpA, Trieste Italy
5:45 PM - NN2.9
Hydrothermal Synthesis of Nano-BaTiO3 Particles using Titanate Nanotubes Precursors – A Kinetic Study.
Paula Vilarinho 1 , Florentina Maxim 1 , Paula Ferreira 1 , Ian Reaney 2 Show Abstract
1 Department of Ceramics and Glass Engineering, University of Aveiro, Aveiro Portugal, 2 Department of Engineering Materials, Univeristy of Sheffield, Sheffield United Kingdom