bluuebunny/crossref_metadata_2025_split huggingface dataset:
Theory of Scanning Probe Microscopy of Carbon Nanostructures
Authors: Meunier Vincent , Kalinin Sergei , Lambin Philippe 
Published: April 2011

ABSTRACTExperimental techniques for SPM imaging and spectroscopy of low-dimensional systems have significantly progressed in recent years. At the same time, new simulation methods and computational techniques have allowed the development of a theoretical basis to the interpretation and understanding of the measurements. In this contribution, we concisely review two state-of-the-art modeling methods for scanning probe microscopy, as applied to carbon nanostructures.
Raman and Rayleigh Smart Imaging of Nanophases and Nanosized Materials. Alternatives Techniques to SEM, TEM and AFM ?
Authors: Colomban Philippe , Havel Mickaël 
Published: April 2011

ABSTRACTThe imaging of nanostructural and topological variations on mechanically or chemically aged SiC materials has been performed using non-destructive Raman and Rayleigh μ-spectrometries. The case of a Hi-Nicalonf/(SiC/BN/C)m composite, corroded under alkali and oxidizing environment (modelled using molten NaNO3), is discussed. It is shown for the first time that Rayleigh imaging offers a competitive alternative to AFM measurements for un-prepared, very corrugated surface of materials containing carbon as a second phase. A comparison is made to the analysis of μ-indented areas performed on a polished section of the Ø∼140 μm SCS-6™ Textron SiC fibre. The “smart” Raman images allowed determining the strain distribution within the whole indented area.
The μ-TA (Scanning Thermal Mcroscopy) - a tool for quantitative surface analysis and surface treatment
Authors: Fischer Hartmut 
Published: April 2011

ABSTRACTThe analytical technique micro-thermal analysis (μ-TA) will be introduced and evaluated. It combines the visualisation power of atomic force microscopy (AFM) and it's ability to image topography, phase shifts, friction, stiffness, and adhesion with the characterisation capabilities of thermal analysis (thermal conductivity, micro-differential thermal analysis and micro-thermo mechanical analysis) resulting in a characterisation of surfaces with respect to their thermal and thermo-mechanical properties. The scanning mode may be used for the inspection of surfaces with respect to their thermal properties using a scanner with an active thermal sensor (heater, height and thermal sensor) as probe (tip), simultaneously acquiring topography, thermal conductivity and thermal diffusivity images. A second mode gives the option to perform a ocal thermo-mechanical analysis of discrete areas of a few square microns (L-TMA and L-CA), and detects at the same time during heating in contact mode changes of the sensor position and the heat flow to the sample in a very short time. Any thermodynamic phase transition, connected with a change in mechanical properties (softening, expansion, melting) and thermal properties (heat of fusion, change of heat capacity) will thus be detected by both methods. Applications for the analysis of especialy soft materials are presented and critically discussed. Moreover, the use of the instrument for controlled surface treatment is demonstrated resulting in the creation of super smooth polymeric surfaces. Furthermore, attempts to determine thermal conductivity's on surfaces on a quantitative matter wil be presented and discussed.
Materials analysis by aberration-corrected STEM
Authors: Krivanek Ondrej L. , Bacon Neil J. , Corbin George C. , Dellby Niklas , McManama-Smith Andrew , Murfitt Matthew F. , Nellist Peter D. , Szilagyi Zoltan S. 
Published: April 2011

ABSTRACTElectron-optical aberration correction has recently progressed from a promising concept to a powerful research tool. 100–120 kV scanning transmission electron microscopes (STEMs) equipped with spherical aberration (Cs) correctors now achieve sub-Å resolution in high-angle annular dark field (HAADF) imaging, and a 300 kV Cs-corrected STEM has reached 0.6 Å HAADF resolution. Moreover, the current available in an atom-sized probe has grown by about 10x, allowing electron energy loss spectroscopy (EELS) to detect single atoms. We summarize the factors that have made this possible, and outline likely future progress.
Transmission electron microscopy study of domain structures in ferroelectric SrBi2Nb2O9 ceramics
Authors: Karthik C. , Ravishankar N. , Varma K.B.R. 
Published: April 2011

ABSTRACTA transmission electron microscopy study has been carried out on the domain structures of SrBi2Nb2O9 (SBN) ferroelectric ceramics which belong to the Aurivillius family of bismuth layered perovskite oxides. SBN is a potential candidate for Ferroelectric Random access memory (FeRAM) applications. The 90° ferroelectric domains and antiphase boundaries (APBs) were identified with dark field imaging techniques using different superlattice reflections which arise as a consequence of octahedral rotations and cationic shifts. The 90° domain walls are irregular in shape without any faceting. The antiphase boundaries are less dense compared to that of SrBi2Ta2O9(SBT). The electron microscopy observations are correlated with the polarization fatigue nature of the ceramic where the domain structures possibly play a key role in the fatigue- free behavior of the Aurivillius family of ferroelectric oxides.
Surface engineering of SrTiO3 (111) substrates for the epitaxial growth of BLT films
Authors: Suh Ju Hyung , Lee Yong Seok , Park Chan-Gyung 
Published: April 2011

ABSTRACTThe optimized surface termination of SrTiO3 (111) substrates was investigated and the effects of the terminated SrTiO3 (111) substrate on the growth characteristics of epitaxial Bi4−xLaxTi3O12 (BLT) films were evaluated. It was found that etching in buffered HF (BOE) solution for 2min provides a stable etching condition for SrTiO3 (111) substrates and that etching is an important factor for the formation of terrace structures. The microstructure of BLT films grown on the terminated substrate revealed a flat surface morphology and well-defined interfacial structure in comparison with BLT films grown on non-terminated substrate. Therefore, surface termination is a crucial factor for determining the quality of film morphology and interfacial structure.
Effect of Simulated Body Fluid on the Microstructure of Ferrimagnetic Bioglass-Ceramics
Authors: Papanearchou N. I. , Leventouri Th. , Kis A. C. , Hotiu A. , Anderson I. M. 
Published: April 2011

ABSTRACTThe effect of simulated body fluid (SBF) on the structure and microstructure of ferrimagnetic bioglass ceramics (FBC) was investigated in series of samples in the system of the oxides [0.45(CaO, P2O5) (0.52-x)SiO2 xFe2O3 0.03Na2O], with X = 0.05, 0.10, 0.15, 0.20. Physical properties of the materials were studied as a function of processing parameters and time of immersion in SBF by x-ray diffraction (XRD) and scanning electron microscopy (SEM) with energy dispersive x-ray spectroscopy (EDS). The in vitro experiment showed that bioactivity of the FBC varies with the composition of the oxides, heat treatment, and time of exposure in SBF in a non-systematic way. A surface layer of Si, P, Ca partially covers the Fe, O dendrites, while formation and size of pores is determined by the specific processing parameters of the materials.
Pair Distribution Function Analyses of Structural Relaxation in a Zr-Based Bulk Metallic Glass
Authors: Morrison Mark L. , Dmowski Wojtek , Wilson Timothy W. , Liaw Peter K. , Liu Chain T. , Richardson James W. , Maxey Evan R. , Buchanan Raymond A. , Fan Cang , Choo Hahn , Egami Takeshi , Porter Wallace D. 
Published: April 2011

ABSTRACTZr-based alloy ingots with nominal compositions of Zr52.5Cu17.9Ni14.6Al10.0Ti5.0 (at.%), Vitre-loy 105, were isothermally annealed below the glass-transition temperature at 630 K for 10, 20, 30, 40, and 60 minutes in vacuum to obtain samples with various states of structural relaxation and compared to the as-cast state. Structural studies were performed using time-of-flight neutron diffraction followed by pair distribution function (PDF) analyses. Differential scanning calo-rimetry (DSC) was conducted to examine changes in the specific heat, which were correlated to the amount of structural relaxation in the various samples. These samples exhibited increasing structural relaxation with longer annealing times, which was evidenced in the atomic PDF. Relaxation related to the exothermic peak results in changes in the PDF that are consistent with the elimination of short and long inter-atomic distances. Further annealing led to rearrangements in the second atomic shell that may be related to local phase separation.
Self-Diffusion in Chemically Homogeneous Multilayers Using Neutron and Nuclear Resonance Reflectivity
Authors: Gupta Mukul , Gupta Ajay , Chakravarty Sujoy , Gutberlet T. , Wille H.-C. , Leupold O. , Rüffer R. 
Published: April 2011

ABSTRACTNeutron reflectivity is a well-established technique for studying self-diffusion in chemically homogeneous system as neutron scattering lengths are different for isotopes of an element. For x-ray there is no contrast for a multilayer with isotopic abundance. However, placing Mössbauer active nuclei in a chemically homogeneous system, self-diffusion of the constituents can be probed using nuclear resonance scattering of Mössbauer active nuclei. In the present work, we have applied the neutron reflectivity technique for studying the self-diffusion of iron and nitrogen in nano crystalline multilayers of FeN/57FeN and FeN/Fe15N and nuclear resonance reflectivity techniques for studying iron self diffusion in FeNZr/57FeNZr. Both the techniques are complementary to each other and give a unique depth resolution of the order of 0.1 nm. As compared with conventional techniques used for probing self-diffusion, neutron and nuclear resonance reflectivity techniques can be applied at significantly lower temperatures. On the basis of the obtained results the diffusion mechanism in chemically homogeneous multilayers is discussed in the present work.
Dynamic Transition in Proteins and DNA: Role of the Solvent
Authors: Sokolov A. P. 
Published: April 2011

ABSTRACTHydrated proteins and DNA demonstrate a dynamic transition at temperatures TD∼200–230K. Sharp slowing down of protein functions (rate of biochemical reactions) was observed at the same temperature range. These results suggest a direct relationship between the dynamic transition and onset of biochemical activities of proteins. However, the microscopic nature of the dynamic transition in biomolecules remains poorly understood. This contribution presents an overview of neutron scattering and simulations data analyzing dynamics of proteins and DNA. We show that the dynamic transition is related to a “slow” relaxation process that appears in the experimental frequency window at temperatures above TD. Moreover, we show that the dynamic crossover in the solvents controls the activation of the slow process in biological macromolecules. Microscopic details of the slow process and of the dynamic transition are discussed.
Large-Scale Morphology of Dispersed Layered Silicates
Authors: Schaefer Dale W. , Justice Ryan S. , Koerner Hilmar , Vaia Richard , Zhao Chungui , Yang Mingshu , Vale Jim 
Published: April 2011

ABSTRACTUltra small angle x-ray scattering is used to probe the morphology of highly dispersed montmorillonite (MMT) in water and polyamide-66. In water the scattered intensity, I(q) shows a q-2 dependence for q > 0.01 Å-1, where q is the magnitude of the scattering vector. This is as expected for a two dimensional sheet-like object. On larger scales (smaller q) mass-fractal character is evident up to the radius-of-gyration of the individual scattering entities. The scattering profile is interpreted using a semi-flexible sheet model in which flat, disk-like entities of radius = 80 Å (an areal persistence length) are fractally distributed on large scales with a mass fractal dimension of 2.65. These size scales correspond to a scattering entity comprised of one or a few crumpled sheets. No evidence of inter-particle correlations is found at concentrations below the gel point. In polyamide-66 loaded with organically modified MMT long-range fractal behavior is also observed but with larger fractal dimension.
The phase-diagram of Ca2-xSrxRuO4: Relation between crystal distortions and physical properties
Authors: Braden M. , Friedt O. , Schumann O. , Baier J. , Steffens P. , Kriener M. , Lorenz T. , Bourée F. , André G. , Gukasov A. , Radaelli P. G. , Nakatsuji S. , Maeno Y. 
Published: April 2011

ABSTRACTThe phase-diagram of Ca2-xSrxRuO4 has been studied by several diffraction techniques as function of concentration, temperature, pressure and magnetic field. The substitution of Sr through the smaller Ca induces a series of structural phase transitions with a strong impact on the physical properties. The spin triplet superconductor Sr2RuO4 exhibits an undistorted crystal structure, and the Mott-insulator Ca2RuO4 strong structural distortions. For intermediate structural distortions samples stay metallic but with outstanding properties. Throughout the phase diagram we find a close coupling between the crystal structure on one side and magnetic and electronic behavior on the other side.
RECIPROCAL-LATTICE SPACE IMAGING OF X-RAY INTENSITIES DIFFRACTED FROM NANOWIRES
Authors: Sakata Osami , Kitano Akiko , Yashiro Wataru , Sakamoto Kunihiro , Miki Kazushi , Matsuda Akifumi , Hara Wakana , Akiba Shusaku , Yoshimoto Mamoru 
Published: April 2011

ABSTRACTA nondestructive method has been developed for quickly characterizing a 1 D crystalline structure. It required brilliant synchrotron x-rays in grazing incidence and an x-ray 2 D detector. X-ray patterns recorded on the detector showed anisotropically sheet-shape diffraction from NiO nanowires epitaxially grown on an ultra-smooth sapphire (0 0 0 1). Other shots obtained from Bi atomic wires embedded in Si (0 0 1) showed that the wires have a 2 × n superstructure, which indicated that the Bi-dimer bonds were parallel to the wires.
USANS as a Probe of Large-Scale Structure in Attractive Colloidal Glasses of Block Copolymer Micelles
Authors: Crichton Mark A. , Forbes Neil S. , Bhatia Surita R. 
Published: April 2011

ABSTRACTWe have used ultra-small-angle scattering (USANS) and fluorescence microscopy to show the existence of large-scale structure in attractive colloidal glasses composed of block polyelectrolyte micelles. Our systems display evidence of surface scattering, with the scattered intensity I at low scattering vector q scaling as I ∼ qx with x in the range –3 to –4. We believe this is due to surface scattering from large, highly polydisperse aggregates with rough interfaces. USANS may provide an ideal way to distinguish fractal colloidal gels and colloidal glasses.
Nanoindentation of Ion Implanted and Deposited Amorphous Silicon
Authors: Williams J. S. , Haberl B. , Bradby J. E. 
Published: April 2011

ABSTRACTThe deformation behavior of both ion-implanted and deposited amorphous Si (a-Si) films has been studied using spherical nanoindentation, followed by analysis using Raman spectroscopy and cross-sectional transmission electron microscopy (XTEM). Indentation was carried out on both unannealed a-Si films (the so-called unrelaxed state) and in ion implanted films that were annealed to 450°C to fully relax the amorphous film. The dominant mode of deformation in unrelaxed films was via plastic flow of the amorphous phase rather than phase transformation, with measured hardness being typically 75–85% of that of crystalline Si. In contrast, deformation via phase transformation was clearly observed in the relaxed state of ion implanted a-Si, with the load-unload curves displaying characteristic discontinuities and Raman and XTEM indicating the presence of high-pressure crystalline phases Si-III and Si-XII following pressure release. In such cases the measured hardness was within 5% of that of the crystalline phase.
Cross-Sectional TEM Studies of Indentation-Induced Phase Transformations in Si: Indenter Angle Effects
Authors: Wen Songqing , Bentley James , Jang Jae-il , Pharr G. M. 
Published: April 2011

ABSTRACTNanoindentations were made on a (100) single crystal Si wafer at room temperature with a series of triangular pyramidal indenters having centerline-to-face angles ranging from 35° to 85°. Indentations produced at high (80 mN) and low (10 mN) loads were examined in plan-view by scanning electron microscopy and in cross-section by transmission electron microscopy. Microstructural observations were correlated with the indentation load-displacement behavior. Cracking and extrusion are more prevalent for sharp indenters with small centerline-to-face angles, regardless of the load. At low loads, the transformed material is amorphous silicon for all indenter angles. For Berkovich indentations made at high-load, the transformed material is a nanocrystalline mix of Si-I and Si-III/Si-XII, as confirmed by selected area diffraction. Extrusion of material at high loads for the cube-corner indenter reduces the volume of transformed material remaining underneath the indenter, thereby eliminating the pop-out in the unloading curve.
An analytical approach for relating hardness and yield strength for materials with high ratio of yield strength to Young modulus
Authors: Vandeperre Luc J. , Giuliani Finn , Clegg William J. 
Published: April 2011

ABSTRACTFor materials with a high ratio of Y to the elastic modulus, E, experimental data show that the ratio of the hardness to the flow stress decreases from 3 toward 1 as Y / E increases. This behaviour is predicted by finite element calculations but to date analytical expressions have not been able to correctly predict the relation between Y and H nor have they been able to show how the geometry of the indenter is important. Therefore, in this paper the correlation between H and Y for such materials is re-examined using an analytical approach to provide a physical interpretation, which explains the trends observed.
Microbridge Nanoindentation Testing of Plasma-Enhanced Chemical Vapor Deposited Silicon Oxide Films
Authors: Cao Zhiqiang , Zhang Tong-Yi , Zhang Xin 
Published: April 2011

ABSTRACTPlasma-enhanced chemical vapor deposited (PECVD) silane-based oxides (SiOx) have been widely used in both microelectronics and MEMS (MicroElectroMechanical Systems) to form electrical and/or mechanical components. In this paper, a novel nanoindentation-based microbridge testing method is developed to measure both the residual stresses and Young's modulus of PECVD SiOx films. Our theoretical model employed a closed formula of deflection vs. load, considering both substrate deformation and the residual stresses in the thin films. In particular, the non-negligible residual deflection caused by excessive compressive stresses was taken into account. Freestanding microbridges made of PECVD SiOx films were fabricated using bulk micromachining techniques. To simulate the thermal processing in device fabrication, these microbridges were subjected to rapid thermal annealing (RTA) up to 800°C. A microstructure-based mechanism was applied to explain the experimental results of the residual stress changes in PECVD SiOx films after thermal annealing.
INVESTIGATION OF INDENTATION METHODS FOR PROPERTIES DETERMINATION IN HARD FILM – SOFT SUBSTRATE SYSTEMS
Authors: Kennedy M. S. , Moody N. R. , Bahr D. F. 
Published: April 2011

ABSTRACTElastic modulus values of the thin films utilized in three different hard film- soft substrate systems were measured using a combination of traditional and continuous stiffness indentation. These systems were chosen to represent typical systems currently utilized in MEMS and included Si/SU8/W, Si/SiO2/Ti/Pt/PZT, and Si/SiO2/Ti/Pt. The last system was coated with either a compressive or nonstressed Cr film. By taking into account ratio between the creep due to the polymer substrate, SU8, to the unloading rate, the modulus of W was measured to be 400 GPa. The modulus of the SU8 was also determined to be 6 GPa. Comparing both the CSM and traditional indentation for the Si/SiO2/Ti/Pt/PZT system showed that the dynamic motion of the indenter caused pile-up in the PZT and resulting in the overestimation of the PZT modulus. This pile-up is a function of the sinusoidal loading frequency. Instead, the modulus of the PZT was measured by shallow depths of traditional indentation that resulted in the PZT modulus of 100 GPa. The hard film-soft substrate systems were show to follow the same trend as stressed soft-film hard-substrate systems with residual stress. The modulus was over estimated for compressively stressed Cr films.
Nanomechanical and Microstructural Properties of Bombyx mori Silk Films
Authors: Ebenstein Donna M. , Park Jaehyung , Kaplan David L. , Wahl Kathryn J. 
Published: April 2011

ABSTRACTInstrumented indentation and micro-Raman spectroscopy were used to investigate the mechanical and structural properties of Bombyx mori silk films. Twelve different films were prepared from B. mori silk fibroin protein using a variety of post-deposition processing treatments (e.g. soaking in methanol, soaking in water, stretching, and/or enzymatic etching). The results show that different treatments lead to changes in both the conformation of the silk fibroin protein and the mechanical properties of the films.
Nanoscale Characterisation of Salivary Pellicle
Authors: Dickinson Michelle E. , Mann Adrian B. 
Published: April 2011

ABSTRACTSalivary pellicle is an organic biofilm formed by the physisorption of proteins and carbohydrates onto the surface of dental enamel exposed to the oral environment. The pellicle has several key roles in oral physiology including lubrication and reduction of friction between teeth during mastication, as well as chemical protection of the enamel against acidic solutions. However, pellicle proteins are known to react with dietary compounds to cause extrinsic staining on the tooth surface.In this study, nanoindentation and AFM have been used in vitro to examine the acquired salivary pellicle formed in vivo on dental enamel. The mechanical properties, growth, structure and morphology of pellicle grown in vivo on human enamel surfaces have been analysed. In addition, the effects of dietary agents such as polyphenols on the pellicle's morphology and properties have been studied.It was found that initial adsorption of proteins on the enamel surface occurred within 30 seconds of exposure to the oral cavity, with full growth achieved within 2 hours. Differences in the properties of the pellicles such as surface adhesion, and time dependent effects due to polyphenol interaction were measured using nanoindentation. It was seen that the polyphenol interaction has a significant effect on these properties. These results suggest that the stained pellicle is mechanically stiffer, but also less viscous and more fluid like. This could explain why traditional tooth brushing techniques do not efficiently remove this layer.