UScholar Works
 
Filters: Department: "Materials Science & Engineering" Collection: "ir_uspace"
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CreatorTitleDescriptionSubjectDate
151 Liu, FengMechanical stability of ultrathin Ge/Si film on SiO2: the effect of Si/SiO2 interfaceWe perform two-dimensional linear elastic finite element analysis to investigate the mechanical stability of ultrathin Ge/Si film grown on or bonded to SiO2, using imperfect interface elements between Si and SiO2 to model Si/SiO2 interfacial slippage. We demonstrate that the overall composite film i...Ultrathin films; Si/SiO2 interface; Mechanical stability2005
152 Stringfellow, Gerald B.Mechanism for liquid phase epitaxial growth of nonequilibrium compositions producing a coherent interfaceA model is presented for growth by so-called composition pulling, wherein an epitaxial deposit grows coherently but with a composition different from that which would be in bulk equilibrium with the liquid phase from which growth occurs. The breakdown of coherent growth occurs when a dislocation nuc...Lattice-matching overgrowths; Composition pulling; Dislocation interface1977
153 Liu, FengMechanism for nanotube formation from self-bending nanofilms driven by atomic-scale surface-stress imbalanceWe demonstrate, by theoretical analysis and molecular dynamics simulation, a mechanism for fabricating nanotubes by self-bending of nanofilms under intrinsic surface-stress imbalance due to surface reconstruction. A freestanding Si nanofilm may spontaneously bend itself into a nanotube without exter...Nanotube formation; Self-bending nanofilms; Surface-stress imbalance2007-04
154 Tiwari, AshutoshMetal-insulator transition in La0.7Sr0.3Mn1-xFexO3We report the effect of Fe doping at the Mn site in La0.7Sr0.3MnO3 oxides. We find that the doping of Fe does not cause any structural change, but the electrical transport in the system is strongly affected. The parent compound La0.7Sr0.3MnO3 shows a resistivity peak at T=Tp (365 K) and behaves as ...Tunneling conductance; Perovskite manganates; Iron doping; Fe doping1999
155 Liu, FengMetal-to-semiconductor transition in squashed armchair carbon nanotubesWe investigate electronic transport properties of the squashed armchair carbon nanotubes, using tight-binding molecular dynamics and the Green's function method. We demonstrate a metal-to-semiconductor transition while squashing the nanotubes and a general mechanism for such a transition. It is the ...Squashed armchair; Carbon nanotubes; Metal-to-semiconductor transition; Electronic transport; Tight-binding molecular dynamics; Squashed nanotubes2003-04
156 Tiwari, AshutoshMetallic conductivity and metal-semiconductor transition in Ga-doped ZnOThis letter reports the metallic conductivity in Ga:ZnO system at room temperature and a metal-semiconductor transition (MST) behavior at low temperatures. Zn0.95Ga0.05O films, deposited by pulsed laser deposition in the pressure range of ~10−2 Torr of oxygen, were found to be crystalline and exhi...Transparent conducting oxides; ZnO; Gallium; Metallic conductivity2006
157 Tiwari, AshutoshMethods of forming three-dimensional nanodot arrays in a matrixNanostructures and methods of making nanostructures having self-assembled nanodot arrays wherein nanodots are self-assembled in a matrix material due to the free energies of the nanodot material and/or differences in the Gibb's free energy of the nanodot materials and matrix materials.Nanodots2006
158 Tiwari, AshutoshMid- to long-wavelength infrared surface plasmon properties in doped zinc oxidesThis work investigates properties of surface plasmons on doped metal oxides in the 2-20 μm wavelength regime. By varying the stoichiometry in pulse laser deposited Ga and Al doped ZnO, the plasmonic properties can be controlled via a fluctuating free carrier concentration. This deterministic approa...2012-01-01
159 Stringfellow, Gerald B.Miscibility gaps and spinodal decomposition in III/V quaternary alloys of the type AxByC1−x−yDThermodynamic concepts have been developed for the calculation of solid-phase miscibility gaps and spinodal decomposition in quaternary alloys of the type AxByC1−x−yD. These concepts have been applied to the analysis of III/V quaternary alloys using the delta-lattice-parameter (DLP) solution mod...Thermodynamics; Quartenary alloys; Coherent decomposition1983-01
160 Scarpulla, MichaelMn L3,2 x-ray absorption and magnetic circular dichroism in ferromagnetic Ga1-xMnxPWe have measured the x-ray absorption and x-ray magnetic circular dichroism (XMCD) at the Mn L3,2 edges in ferromagnetic Ga1−xMnxP films for 0.018≤x≤0.042. Large XMCD asymmetries at the L3 edge indicate significant spin polarization of the density of states at the Fermi energy. The temperatur...X-ray absorption; Gallium Arsenide; Ferromagnetic semiconductors2006
161 Scarpulla, MichaelMn L3,2 x-ray absorption spectroscopy and magnetic circular dichroism in ferromagnetic Ga1-xMnxPWe have measured the X-ray absorption (XAS) and X-ray magnetic circular dichroism (XMCD) at the Mn i32 edges in ferromagnetic Ga1-xMrixP films for 0.018<x<0.042. Large XMCD asymmetries at the L3 edge indicate significant spin-polarization of the density of states at the Fermi energy. The spectral s...X-ray absorption; Ferromagnetic semiconductors; X-ray magnetic circular dichroism (XMCD); Gallium Manganese Phosphide; Gallium arsenide2007
162 Tiwari, AshutoshModification of high potential, high capacity Li2FeP 2O7 cathode material for lithium ion batteriesLi2FeP2O7 is a newly developed polyanionic cathode material for high performance lithium ion batteries. It is considered very attractive due to its large specific capacity, good thermal and chemical stability, and environmental benignity. However, the application of Li2FeP2O7 is limited by its low i...2012-01-01
163 Liu, FengModification of Si(001) substrate bonding by adsorbed Ge or Si dimer islandsHigh-resolution scanning tunneling microscopy studies of the Si(100)-(2 X 1) surface show a heretofore unrecognized distortion of the substrate structure when islands form during the initial stage of growth of either Si or Ge. The distortion, reflecting the influence of strain, extends at least thre...Si(001); Adsorbed Ge; Adsorbed Si; Dimer islands; Substrate bonding; Distortion1998-09
164 Liu, FengModified Timoshenko formula for bending of ultrathin strained bilayer filmsMechanical bending of nanoscale thin films can be quite different from that of macroscopic thick films. However, current understanding of mechanical bending of nanoscale thin strained bilayer films is often limited within the Timoshenko model [Timoshenko, J. Opt. Soc. Am. 11, 233 (1925)], which was ...Timoshenko formula; Bending theory; Ultrathin films; Strained nanoscale thin films; Nanofilms2008
165 Smith, Grant D.Molecular dynamics of a 1,4-polybutadiene melt. Comparison of experiment and simulationWe have made detailed comparison of the local and chain dynamics of a melt of 1,4-polybutadiene (PBD) as determined from experiment and molecular dynamics simulation at 353 K. The PBD was found to have a random microstructure consisting of 40% cis, 50% trans, and 10% 1,2-vinyl units with a number-av...Polybutadiene melt; Molecular dynamics1999
166 Smith, Grant D.Molecular dynamics simulation studies of the influence of imidazolium structure on the properties of imidazolium/azide ionic liquidsAtomistic molecular dynamics simulations were performed on 1-butyl-3-methyl-imidazolium azide [bmim][N3], 1-butyl-2,3-dimethylimidazolium azide [bmmim][N3], and 1-butynyl-3-methylimidazolium azide [bumim][N3] ionic liquids. The many-body polarizable APPLE&P force field was augmented with parameters ...2012-01-01
167 Bedrov, Dmitro; Smith, Grant D.Molecular dynamics simulation study of elastic properties of HMXAtomistic simulations were used to calculate the isothermal elastic properties for b-, a-, and d-octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX). The room-temperature isotherm for each polymorph was computed in the pressure interval 0≤p≤10.6 GPa and was used to extract the initial isot...HMX; Elastic tensors; Isotropic moduli; Polymorphs; Isothermal compression; Lattice parameters2003
168 Bedrov, DmitroMolecular dynamics simulation study of the pressure-volume-temperature behavior of polymers under high pressureIsothermal compression of poly (dimethylsiloxane), 1,4-poly(butadiene), and a model Estane® (in both pure form and a nitroplasticized composition similar to PBX-9501 binder) at pressures up to 100 kbars has been studied using atomistic molecular dynamics (MD) simulations. Comparison of predicted co...2009
169 Bedrov, Dmitro; Smith, Grant D.Molecular dynamics simulations of HMX crystal polymorphs using a flexible molecule force fieldMolecular dynamics simulations using a recently developed quantum chemistry-based atomistic force field [J. Phys. Chem. B 103 (1999) 3570] were performed in order to obtain unit cell parameters, coefficients of thermal expansion, and heats of sublimation for the three pure crystal polymorphs of octa...HMX; Crystal polymorphs; Force field; Coefficients of thermal expansion; Heat of sublimation; Cell parameters2002
170 Smith, Grant D.; Borodin, OlegMolecular-dynamics simulation study of dielectric relaxation in a 1,4-polybutadiene meltWe have carried out atomistic molecular dynamics simulations of a melt of 1,4-poly(butadiene) from temperatures well above the experimentally observed merging of the primary a process and secondary b process down to temperatures approaching the experimentally observed bifurcation temperature. The re...Polymer melts; 1,4-polybutadiene; Chain dynamics; Conformational dynamics2002
171 Ostafin, AgnesMonitoring the synthesis and composition analysis of microsilica encapsulated acetylacetonatocarbonyl triphenylphosphinerhodium catalyst by inductively coupled plasma (ICP) techniquesAbstract-A novel technique to monitor the synthesis process of encapsulated acetylacetonatocarbonyl triphenylphosphinerhodium within a microsilica nanoshell has been studied using inductively coupled plasma (ICP) techniques. Nanospheres sized around 50-100 nm were obtained and ICP was used to quanti...2006
172 Scarpulla, MichaelMutual passivation of group IV donors and nitrogen in diluted GaNxAs1 x alloysWe demonstrate the mutual passivation phenomenon of Ge donors and isovalent N in highly mismatched alloy GaNxAs1-x doped with Ge. Layers of this alloy were formed by the sequential implantation of Ge and N ions followed by pulsed laser melting and rapid thermal annealing. The mutual passivation effe...Highly mismatched alloys; Passivation; Gallium arsenide2003
173 Ostafin, AgnesNanomedicine making headway across the blood brain barrierNanotechnological advances implemented by nanomedicine have allowed significant development of imaging strategies, therapeutics and theranostics for many severe and life threatening diseases such as brain tumors, Alzheimer's disease, Parkinson's disease and other neurological disorders. The Blood-Br...2012-01-01
174 Liu, FengNanostressors and the nanomechanical response of a thin silicon film on an insulatorPseudomorphic three-dimensional Ge nanocrystals (quantum dots) grown on thin silicon-on-insulator substrates can induce significant bending of the silicon template layer that is local on the nanometer scale. We use molecular dynamics simulations and analytical models to confirm the local bending of...Nanostressors; Nanomechanical response; Thin silicon film2002-09
175 Tiwari, AshutoshNanostructured DLC-Ag composites for biomedical applicationsWe have synthesized novel diamondlike carbon coatings with silver nanoparticles embedded into the DLC film. The size of silver nanoparticles that are confined into layered structures has been varied from 5 nm to 50 nm using an ingenious pulsed laser deposition technique. The size of nanoparticles wa...Diamondlike carbon coatings; Nanocrystals2003
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