bluuebunny/crossref_metadata_2025_split huggingface dataset:
Analysis Of Oxygen Distribution In Interfaces In SiC Whisker Reinforced Si3 N4-Based Composites.
Authors: Das Chowdihury K. , Carpenter R. W. , Braue W. 
Published: March 2011

ABSTRACTDiscontinuous and continuous interfacial layers at the whisker/matrix and grain boundary interfaces in silicon carbide whisker reinforced silicon nitride based composites were investigated by high resolution electron imaging and analytical microscopy. Wide differences in chemical and structural widths of the interfaces were observed.
The Effect Of Trace Element Segregation To Fe/Sapphire Interfaces
Authors: Pope D. P. , Smith M. A. 
Published: March 2011

ABSTRACTThe effects of segregation of tramp impurities such as sulfur on metal/ceramic bonding is discussed. Microstructural and chemical information is given for the Fe/sapphire interface. The segregation behavior of the interface is evaluated between 500–800 °C. The interfacial structure is shown to be important to the segregation behavior. A possible link between the segregation of sulfur and interface void formation is presented.
Effects Of Cation Segregation At Oxide Grain Boundaries On Grain Boundary Diffusion And Oxidation Kinetics Of Nickel
Authors: Cotelia C. M. , Bennett M. J. , Garratt-Reed A. J. 
Published: March 2011

ABSTRACTThe oxidation behavior of Ni, implanted with either divalent Ce2+ or trivalent Y3+, has been studied to test the general applicability of the grain boundary segregation explanation for the reduction in rate of oxidation resulting from reactive element additions to metals that form protective oxide scales. Oxidation of Ce- and Y-implanted Ni at 900°C resulted in grain boundary segregation of the implanted species in the NiO scales formed. The rate of oxidation of Ni was reduced and there was evidence for a change in oxidation mechanism. Additionally, the grain size of the oxides was much smaller. All the observations were entirely consistent with a reduction in cation transport resulting from segregation of foreign ions at the oxide grain boundaries. These results on Ni are compared with recent studies of Ce- and Y-implanted Cr to draw general conclusions about the relationship between grain boundary segregation in oxides and the reactive element effect on oxidation.
Kinetics Of Dopant Distribution In Lpe Grown GaAs Epi-Layer
Authors: Okamoto Y. , Akagi Y. , Koba M. 
Published: March 2011

SUMMARYWe have studied the distribution and diffusion of Te, Mg, and Zn dopants in GaAs which was grown by an LPE process. It was found that the distribution of the dopant atoms of Te and Zn in the Te-doped n-type epi-layer on the Zn-doped p-type substrate showed a sharp and clear interface. In contrast, the dopant distribution of Mg and Zn in the Mg-doped p-type epi-layer on the Zn-doped substrate indicated a diffuse interface because of significant interdiffusion. The X-ray diffraction of these epi-layers and substrates revealed that the Mg-doped epi-layer showed rather poorer crystalline quality than the other specimens. These experimental results can be accounted for by a model of charged vacancies in a p-type GaAs.
Preferred Orientations in Metal/Non-Metal Interface Systems
Authors: McCafferty K. , Soper A. , Shirokoff J. , Erb U. 
Published: March 2011

ABSTRACTResults of recent studies of preferred orientations for metal/non-metal interface systems are presented and discussed in terms of some of the general concepts derived from interface structure models. The limitations of geometric models used to predict preferred orientations for metal/ionic crystal interfaces are demonstrated, and the effects of temperature and impurity segregation on the low energy interfaces for metal/glass interfaces are discussed.
The Role Of Thermomechanical Energy In Diffusion Kinetics And Crystallinity Of Mechanically Alloyed Titanium Aluminides
Authors: Dahl Laura , Shepler Mark , Nash Alexis S. 
Published: March 2011

ABSTRACTMechanical alloying, MA, is an amorphization technique which involves a solid state reaction below the crystallization temperature. This technique is capable of producing a more homogeneous and fine microstructure with improved mechanical properties. Amorphization of Titanium aluminide binary system, in the range of 45–65 at % Al is possible under optimized milling conditions since in this range the mixture has a large negative heat of mixing. This system is considered suitable for human implant applications for its light-weight, wear resistance, corrosion resistance, strength-to-weight ratio and biocompatibility.
Interfacial Structure and Evolution in Mesotaxial CoSi2/Si Heterostructure
Authors: Hull S. R. , Hsieh Y. F. , White A. E. , Short K. T. 
Published: March 2011

ABSTRACTWe describe the evolution and microstructure of Si/CoSi2/Si (100) and (111) heterostructures formed by Co+ ion implantation into Si substrates (“mesotaxy”), followed by high temperature annealing. It is shown that the CoSi2 precipitate nucleation and ripening process, and eventual coalescence into buried layers, is controlled by interfacial structure and energetics. Understanding and control of these processes allows for the first time synthesis of otherwise almost identical CoSi2 buried layers with either twinned or untwinned CoSi2/Si(111) interfaces.
Interfacial Structures of MoSi2-Mo5Si3 Eutectic Alloys
Authors: Kung H. , Chang H. , Gíbala R. 
Published: March 2011

ABSTRACTScript lamellar microstructures which occur in certain intermetallic eutectic alloys, such as in the Mo-Si system, may provide desirable mechanical properties. Arc-melted specimens of MoSi2-Mo5Si3 eutectic alloys which exhibit the interlocking lamellar phases were examined in this study. We have observed, by conventional transmission electron microscopy (TEM), an orientation relationship between the MoSi2 and the Mo5Si3 phases, (110)[001]1-2 ‖ (330)[110]5-3, which is consistent with the crystallographic coordinate transformation matrix. High resolution transmission electron microscopy (HRTEM) discloses the interfacial dislocations to be of <100> and 1/2<111> types and the interfaces are regularly faceted. A shear fault which may be consisting of antiphase boundary (APB)-coupled 1/6<331> superpartial dislocations was observed in MoSi2 grain near the interface. Crack propagation paths suggest that the eutectic has a strong, low energy interface which is consistent with the observations of a low index orientation relationship between the two phases and the faceted interfacial structures.
Comparison of Different Thickness Measurements of Oxide Films on Silicon
Authors: Kao Shou-Chen , Doremus Robert H. 
Published: March 2011

ABSTRACTThe thermal oxidation of silicon in dry oxygen is examined with three different thickness measurements: Ellipsometry, transmission electron microscopy and step-profile measurements. The oxidation kinetics follow a linear-parabolic relationship throughout the measured thickness range. Previous deviations from linear-parabolic behavior result from inaccurate ellipsometer measurements of film thickness for films thinner than 0.05 /zm.
The Role of Chemical Interactions in the Stability of Artificial Metallic Superlattices
Authors: Sluiter M. , Turchi P.E.A. 
Published: March 2011

ABSTRACTAtom by atom deposition techniques, such as magnetron sputtering, make possible the synthesis of artificial superlattices with composition modulations in one dimension on an atomic scale[1]. Generaily, elastic effects (lattice mismatch) and chemical affinity (ordering or clustering tendencies are recognized as the most important driving forces for the thermodynamic stability of such materials. In this study the chemical aspect of stability will be examined using a formalism based on first-principles electronic structure calculations developed originally for bulk alloys. The formalism has been applied to a number of systems with fee and bec transition metals as constituents. In some cases the stability of artificial superlattices was found to depend in a rather surprising and unexpected way on the direction and wavelength of the composition modulation.
The Control of Interfacial Reactions Via Length Scales of Ultrathin-Film Modulated Composites
Authors: Fister Loreli , Novet Thomas , Grant Christopher A. , McConnell John , Johnson David C. 
Published: March 2011

ABSTRACTInterfaces are difficult to probe because the volume of the interfacial region is exceedingly small compared with the bulk. Our approach is sequentially to deposit thin (5–50Å) elemental layers to create a unique initial reactant. Due to the short modulation length, the interfaces constitute a large fraction of the total composite. Composites modulated below a critical repeat unit length are found to evolve into homogeneous amorphous alloys. Composites modulated above this critical distance behave like bulk diffusion couples. The layered nature of the starting reactant permits the evolution of the interfacial structure to be followed in a quantitative manner using x-ray diffraction. Distinct differences in the evolution of the interfaces above and below the critical distance are observed. This approach to studying interfaces also permits the direct and selective synthesis of crystalline compounds. Nucleation is the rate-limiting step in the formation of a crystalline material from an amorphous alloy, and the phase formed is strongly influenced by the stoichiometry of the homogeneous amorphous alloy. Results from studies of molybdenum-selenium and iron-silicon ultrathin-film composites will be discussed.
Characterization of Pd/V Multilayer Structures by High-Angle Annular Dark-Field Microscopy and High Resolution Tem
Authors: Liu J. , Cheng Y. , Lewen G. D. , Stearns M. B. 
Published: March 2011

ABSTRACTThe structures of e-beam evaporated Pd/V multilayer thin films, which were fabricated at different substrate temperatures, have been characterized by high-angle annular dark-field microscopy and high resolution electron microscopy techniques. X-ray scattering and crosssectional electron microscopy showed that both the Pd and V layers are composed of small textured crystallites with dominant orientations of Pd (111) and V (110). It is found that Pd/V multilayers with high chemical modulation can be fabricated at substrate temperatures around 350 K and at a deposition rate of 0.2 nm/s. Here high-angle annular dark-field microscopy has been shown to provide direct information about the compositional variation of the interlayers of these ML.
High Resolution Electron Microscopy Observations About The Interface Structure In A Ti/TiN Multilayer Material
Authors: Ning X. G. , Guo L. P. , Huang R. F. , Gong J. , Yu B. H. , Wen L. S. , Ye H. Q. 
Published: March 2011

ABSTRACTThe interface structure in a Ti/TiN multilayer material has been investigated by high resolution transmission electron microscopy (HRTEM). It was shown that the α-Ti and β-TiN layers consisted of many cylindrical crystals growing along the close packed directions normal to the surface of a stainless steel. There existed specific orientation relationship at the Ti/TiN interfaces without transition layers: (111)TiN ‖ (001)Ti, [110]TiN ‖ [100]Ti. However there was no such orientation relationship at the Ti/TiN interfaces with TixN (x >1) transition layers.
Microstructural Evolution Of Ti/Ni AND Ni/Ti Bilayer Thin Films
Authors: Haftek E. , Tan M. , Waknis A. , Barnard J. A. 
Published: March 2011

ABSTRACTThe growth and microstructural evolution of sputtered Ti/Ni and Ni/Ti bilayer thin films have been investigated as a function of Ti and Ni layer thicknesses in as-deposited and annealed states (280°C for 60 minutes) by transmission electron microscopy (TEM). The Ti layer thickness was varied systematically from 4.9 to 29.4 nm while the Ni thickness was varied from 3.2 to 19.2 nm. Carbon coated Cu TEM grids were used as substrates. Microstructural characteristics of the bilayers were found to be deposition sequence dependent. Ti/Ni bilayers exhibit a finer microstructure than N/T especially for the thicker films. Intergranular cracking is observed in the Ti/Ni sequence. In both deposition sequences the presence of Ni promotes the crystallization of Ti in the as-deposited state. By contrast, single layer Ti films deposited under the same sputtering conditions remain amorphous up to 9.8 nm thick. The Ti{002} electron diffraction ring is present in all of the bilayers even those with the thinnest Ti layers. Additional Ti rings, {010} and {011}, develop in bilayers with thicker Ti layers. In both bilayer systems a tensile stress parallel to the film plane is present in the Ni layer. Annealing removes structural defects and relieves the stress. A large increase in Ni{111} spacing can be attributed to dissolution of Ti atoms into the Ni lattice. Annealing also produces evidence of grain growth, intermetallic compound formation, and amorphization in both Ti/Ni and Ni/Ti samples.
Low-Temperature Device-Quality SiO2/Si (100) Interfaces Prepared By A Combined Remote Plasma Oxidation-Deposition Process
Authors: Yasuda T. , Ma Y. , Lucovsky G. 
Published: March 2011

ABSTRACTGate-quality SiO2/Si(100) interfaces were reproducibly fabricated using a two-step remote plasma-assisted oxidation/thin-film deposition processing sequence at temperatures between 200 and 300°C. The pre-deposition oxidation creates approximately 0.5nm of SiO2, and produces an SiO2/Si interface with a midgap trap density of ∼1.3×1010cm−2eV−1. The MOS capacitors prepared by this technique have properties comparable to those with thermal oxides grown at 850–1050°C. These capacitors also show a longer minority-carrier life time in the underlying Si than samples prepared using other pre-deposition treatment methods.
The Properties of Twinning Dislocations in Alpha-Titanium Simulated With A Many-Body Interatomic Potential
Authors: Bacon David J. , Serra Anna 
Published: March 2011

ABSTRACTComputer simulation of the atomic structure and movement of twinning dislocations in four twin boundaries in the h.c.p. metal α-Ti is described. These dislocations have the form of steps on the twin boundary, and whereas some have cores which are very widely spread over the interface, others are only an interatomic spacing or so across. These configurations are determined mainly by whether or not atomic shuffles are required to restore the h.c.p. crystal structure when the dislocation is introduced. The mobility of the dislocations is also controlled by the same effect, and is found to correlate well with experiment.
Alloy Effects And Extended Solubilities In Binary Mixtures Of Nanometer-Sized Fe-Cu Crystals
Authors: Eckert J. , Birringer R. , Holzer J. C. , Krill C. E. , Johnson W. L. 
Published: March 2011

ABSTRACTBinary mixtures of Fe-Cu powders in the range of 10–95 at.% Fe have been prepared by mechanical alloying and investigated by x-ray diffraction, differential scanning calorimetry (DSC), and transmission electron microscopy (TEM). The final grain sizes of the powders vary between 6 and 20 nm, and depend on the composition of the material. Indications for the formation of single-phase alloys with up to 60 at.% Fe in Cu and 20 at.% Cu in Fe have been found although the Fe-Cu system exhibits only vanishingly small solid solubilities under equilibrium conditions. Between 60 at.% and 80 at.% Fe a two-phase region of fee and bec solid solutions exists. Alloy formation is discussed with respect to the thermodynamic conditions of the material. The influence of the large grain boundary fraction, as well as the role of internal strains and stored enthalpies introduced by ball milling, is critically assessed.
Synthesis And Characterization Of Ball-Milled Nanocrystalline Fcc Metals
Authors: Eckert J. , Holzer J. C. , Krill C. E. , Johnson W. L. 
Published: March 2011

ABSTRACTNanocrystalline fee metals (Al, Cu, Ni, Pd, Rh, Ir) have been prepared by ball milling. The development of the microstructure is investigated by x-ray diffraction, differential scanning calorimetry (DSC), and transmission electron microscopy (TEM). The final grain sizes range from 6 to 22 nm and scale with the melting point and the bulk modulus of the elements: metals with higher melting point and bulk modulus have a smaller final grain size. From this a general relation between the deformation mechanism during ball milling and the ultimate grain size achievable by this technique is inferred. With decreasing grain size the lattice strain is enhanced and deformation enthalpies of up to 40 % of the heat of fusion are stored in the material. The contributions of the lattice strain and of die excess enthalpy of the grain boundaries to the stored enthalpies are critically assessed. The kinetics of grain growth are investigated by mermal analysis. The activation energy for grain boundary migration is derived from a modified Kissinger analysis and estimates of the grain boundary enthalpy are given.
Structural Relaxations At Metal / Metal Oxide Interfaces
Authors: Mader W. 
Published: March 2011

ABSTRACTRecent work is reviewed on the structure of metal/metal oxide interfaces in model systems with well defined orientation relationships and boundary inclination. Structural relaxations established upon interface formation may be described as misfit dislocations which can be investigated using conventional and high resolution TEM. The conditions for obtaining informations at an atomistic scale using HRTEM are critically discussed. Specifically, geometrical restrictions are found to be critical in HRTEM study of {111} interfaces in fee metal -fee oxide systems. Different misfit dislocation networks at {100} interfaces in fee metal - fee oxide systems were observed which may be correlated to the relative strength of metal-anion and metal-cation bonds at the interface. In strongly interacting systems misfit dislocations can possess an equilibrium stand-off distance from the interface. In the system Nb-Al2O3 the interface is shown to be coherent by the registry of atomic columns adjacent to the interface. In this configuration energy is minimized by unbroken strong interfacial bonds and misfit localization in the elastically softer metal.
Metal-Oxide Interfacial Structures Produced By Internal Oxidation
Authors: Lu P. , Tung I.-C. , Cosandey F. 
Published: March 2011

ABSTRACTInterfaces in Cu/MgO, Pd/MgO, Pd/Al2O3, Ni/NiAl2O4 and Ni/Al2O3 systems produced by internal oxidation have been studied by transmission electron microscopy. For the Cu/MgO system, the MgO particles, with a cube-on-cube orientation with respect to Cu matrix, are faceted with principal faces parallel to {111} lattice planes of Cu and MgO. For the Pd/MgO system, the MgO particles, with a cube-on-cube orientation with Pd matrix, are faceted with interfaces parallel to the {100} and {111} lattice planes of MgO and Pd. Additional plate-like MgO particles with main facets parallel to {111} lattice planes possess a twin orientation relationship with the Pd matrix. Interfaces in Cu/MgO and Pd/MgO systems are all partially coherent with interfacial misfit dislocations. For the Pd/Al2O3 system, various transition oxide phases such as η, δ, and θ-Al2O3 and stable α-Al2O3 phase have been observed. The [1100] direction of α-Al2O3 is parallel to the [110] direction of Pd and the (0001) plane of α-Al2O3 is parallel or nearly parallel to the (110) plane of Pd. The NiAl2O4 spinel phase and Al2O3 phases are formed in Ni-Al alloys under two different oxidation conditions. The NiAl2O4 particles have a plate-like morphology with a cube-on-cube orientation relationship with the Ni matrix, while Al2O3 particles are randomly oriented.
Experimental Determination Of Relaxation Of Interphase Interfaces In Oxide Eutectics
Authors: Dravid Vinayak P. , Ravikumar V. , Dhalenne G. , Revcolevschi A. 
Published: March 2011

ABSTRACTInterphase interfaces in the directionally solidified eutectics.(DSEs) of NiO-ZrO2(CaO), NiO-Y2O3 and MnO-ZrO2 have been investigated using a variety of TEM techniques. The unique lamellar morphology of the DSEs allows characterization of interfaces and identification of relaxations along multiple directions, aiding visualization of interface structure in three dimensions. Possible low energy interface orientations were identified through examination of facets. The low energy interface planes almost invariably correspond to polar surfaces of adjacent crystals. An attempt has been made to experimentally identify the variety of interfacial relaxation mechanisms using a variety of analytical TEM techniques and only HRTEM results are summarized in this paper. It was found that most of the DSE systems exhibit very little relaxation and possess tight interface cores.
TEM Study of (015) Growth Twins in The Bi-Sr-Ca-Cu-O Superconductors Obtained by Melt Quench Technique
Authors: N Ohnishi , M Sankararaman , H Sato 
Published: March 2011

ABSTRACTA new type of twin structure is found to exist quite commonly in the Bi2Sr2CaCu2O8+δ superconductor obtained by annealing melt quenched amorphous precursors. From transmission electron microscopy and electron diffraction, the twinning plane is determined to be the (015) plane (disregarding the period of incommensurate modulation in the b-direction). Further, the twin boundary is found to be coherent with a specific coincidence condition. The analysis of the morphologies indicates that the twins nucleate at the early stages of the grain growth in these materials.
Simulation of Y-Ba-Cu-0 Epitaxial Growth and Microstructure Formation
Authors: Burmester C. P. , Wille L. T. , Gronsky R. 
Published: March 2011

ABSTRACTThe results of systematic computer simulations of the deposition and growth of Y-Ba-Cu-0 thin films is reported. The deposition process is modeled by means of a three-step Monte Carlo simulation incorporating one sorption deposition mode and two modes of film annealing addressing surface and bulk diffusion. The simulation is used to investigate the evolution of surface morphology and film microstructure, growth rate anisotropy, and the dependence of film texture on deposition parameters. Characteristic defects and surface morphologies observed by simulation are found to be in good agreement with those observed experimentally. It is observed that surface kinetics can dominate the evolution of film microstructure.
Defect Structures in Epitaxially Grown InAs Films on InP Substrates
Authors: Ballal A. K. , Salamanca-Riba L. , Partin D. L. , Heremans J. , Green L. , Fuller B. K. 
Published: March 2011

ABSTRACTIn this paper we study the lattice-mismatch induced defect structures of InAs films grown on semi-insulating InP substrates using metal organic chemical vapor deposition. The defect structure studies were carried out on films of equal total thicknesses but for different duration for nucleation of a layer of InAs deposited at low temperature on the substrate. Misfit strain is caused by the inherent lattice mismatch of approximately three percent and this is partially relieved by the generation of misfit dislocations at the film/substrate interface. Transmission electron microscopy studies show the presence of an intrinsic strain and the generation of thermal etchpits at the heteroepitaxial interface. Our studies show that there is a direct correlation between the density of dislocations generated at the film/substrate interface and the duration of nucleation of the film on the substrate. Dislocation densities at the surface of the InAs films and at the heteroepitaxial interface differed by almost two orders of magnitude. High resolution electron microscopy reveals abrupt and sharp interfaces in films with thick nucleation layers and also confirms that the lattice mismatch is partially accommodated by the generation of misfit dislocations at the film/substrate interface.