Materials Literature
按标题、摘要、年份、主题和来源检索公开元数据。结果保留作者、摘要、分类与原始来源链接。
Phonon spectra for graphitic sheets of carbon, BN, and ${\mathrm{BC}}_{2}$N are computed and studied. The dynamical matrices are constructed from force constants obtained by performing supercell Hellmann-Feynman force calculations within the framework of the local-density approximation. The calculated phonon dispersio…
We report the experimental investigation of the optical properties of porous silicon embedded in a planar microcavity structure in which both the active layer and the two Bragg reflectors are fabricated by electrochemical processing of a p-type porous silicon wafer. By tuning the cavity resonance energy around the max…
The kinetics of carbon nanotube growth under arc discharge conditions were investigated over different length and time scales using complementary numerical techniques. Relaxation by ab initio molecular dynamics (Car-Parrinello method) shows that large electric fields present at the tube tips are not the critical facto…
A detailed study of the properties of ${\mathrm{Pr}}_{1\mathrm{\ensuremath{-}}\mathit{x}}$${\mathrm{Ca}}_{\mathit{x}}$${\mathrm{MnO}}_{3}$ shows that for a range of compositions (0.3\ensuremath{\le}x0.5) there is a first-order magnetic-field-induced insulator-metal transition. For the x=0.4 composition the magnetic an…
The optical properties (interband and intraband absorption) of a recently proposed structure---twinning superlattices---in diamond-type and zinc-blende-type semiconductors are calculated and discussed. The conduction-band intraband absorption is found to be rather weak, but the intraband absorption between the valence…
The dependence of the nonlinear refractive index n2 on glass compositions for optical fibers is clarified. The relation between n2 and germanium- or fluorine-doped SiO2 is calculated on the basis of the measurement of n2 at 1.55 μm with the improved cross-phase-modulation method, taking into account the radial distrib…
Magnetic properties of carbon nanotubes (CN's) are studied in a k · p model. In a magnetic field perpendicular to the tube axis, the magnetization is essentially determined by that of a graphite sheet, while it is induced also by the Aharonov-Bohm (AB) effect in a parallel field. The AB effect manifests itself in the…
Recently, octahedron structures have been found in the Czochralski-silicon substrate surface layer just under the oxide defects. An attempt is made to characterize these structures by analysis with transmission electron microscopy and energy-dispersive x-ray spectroscopy. Several results indicate that the structure is…
We relate the static conductivity of carbon nanotubes to the static in-plane conductivity of a graphite sheet and conclude that isolated single-wall nanotubes are excellent conductors. In contrast, multiwall tubes at low doping may possess conductivities substantially below that of the sum of the constituent tubes. Th…
We have studied metallic ${\mathrm{SrVO}}_{3}$ and ${\mathrm{CaVO}}_{3}$ by inverse photoemission and high-resolution photoemission. In going from Sr to Ca, considerable spectral weight is transferred from the coherent band to the upper and lower Hubbard bands. Meanwhile, the overall intensity rather than the width of…
The electronic structure of ${\mathrm{PrNiO}}_{3}$ has been studied by photoemission and x-ray-absorption spectroscopy. By analyzing the spectra using configuration-interaction calculations on a ${\mathrm{NiO}}_{6}$ cluster model, it has been found that the charge-transfer energy \ensuremath{\Delta} is \ensuremath{\si…
Statics of 90° domain structures formed in a thin tetragonal film epitaxially grown on a cubic substrate is studied theoretically on the basis of a rigorous solution of the associated elasticity problem. Inhomogeneous internal stresses existing in the strained polydomain epitaxy are calculated by the method of fictiti…
The influence of the electrodes on the dielectric behavior and especially on the leakage behavior of SrTiO3 thin films was investigated by impedance analysis. Based on measurements on thin films with different electrode materials the work function of these materials was found to determine the leakage currents. The mai…
The symmetry and electronic structure of the Mn impurity in ZnS nanocrystals have been studied with electron paramagnetic resonance (EPR). Experiments were performed at 9 and 35 GHz on crystals with an average diameter of 35 \AA{}. Changes in the spectra over a period of months indicate a gradual degeneration of the p…
We report the results of transmission electron microscopy on the layered rare-earth tritellurides R${\mathrm{Te}}_{3}$ (R=La,Sm,Gd,Tb,Dy,Ho,Er,Tm). Through electron diffraction we have identified superlattice reflections indicating the presence of incommensurate distortions, consistent with sinusoidal atomic displacem…
dc sputtered indium-tin-oxide films have been excimer laser irradiated at subablation threshold fluences (<510 mJ/cm2). Optical characterization of irradiated products has been performed aiming at resolving the finer structure appearing in the IR–visible absorption spectra, as a function of laser fluence, and a…
X-ray diffraction from simple monocrystalline and epitaxial multilayered surface gratings will be described theoretically by use of a distorted wave Born approximation of second order. The intensity patterns of simple and multilayered gratings have been simulated by this treatment and compared with the kinematical app…
Abstract Waterborne polyurethanes (PUs) were hydrophobically modified using various types of acrylate monomers. PUs having hydroxy ethylacrylate (HEA) terminal groups were first obtained following a prepolymer mixing process. These PU base polymers were then chain extended with acrylate monomers via a radical polymeri…
Abstract Recent work has shown that nylon 6/acrylonitrile–butadiene–styrene (ABS) blends can be made tough by the addition of some polymer additives that are chemically reactive with nylon 6 and physically compatible with the styrene‐acrylonitrile copolymer (SAN) phase of ABS. Imidized acrylic polymers (IA) represent…
Abstract Poly(vinyl chloride) (PVC), PVC/chlorinated polyethylene (CPE), PVC/oxidized polyethylene (OPE), and PVC/CPE/OPE compounds were prepared in a Haake torque rheometer at various temperatures, rotor speeds, and totalized torques (TTQ). The fusion characteristics of these PVC compounds (fusion time, fusion torque…