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。
AlN layers grown on Al2O3 substrates by metalorganic chemical vapor desposition were implanted with high doses (3×1016 cm−2, 250 keV) of Co+, Cr+, or Mn+. Band-edge photoluminescence intensity at ∼6 eV was significantly reduced by the implant process and was not restored by 950 °C annealing. A peak was observed at 5.8…
We have studied crystallization in a system of sedimenting colloids in real space using fluorescence confocal microscopy. During sedimentation a gradient in particle concentration develops at the bottom of the sample container. The presence of the lower boundary wall induces layering in the liquid and, upon increasing…
Collagen model peptide (Pro-Pro-Gly)10 has a triple helical structure and undergoes a thermal transition to a single random coil structure. The transition temperature of the analogous model peptides depends largely on amino acid substitution. Substitution of Pro by 4-hydroxyproline (Hyp) or 4-fluoroproline (fPro) has…
A first-principle investigation of the effects of multiple Si=O bonds at the surface of silicon-based clusters with different sizes has been carried out. Total-energy pseudopotential calculations within density functional theory have been applied varying systematically the number of Si=O bonds at the clusters surface.…
Abstract The compatibility of natural rubber/ethylene‐propylene‐diene monomer (EPDM) blends with and without different compatibilizers was evaluated with viscosity measurements, differential scanning calorimetry, and scanning electron microscopy. The blends were modified with two methods. In the first method, high‐ene…
We report on the in-situ formation of ZnO nanobelts and metallic Zn nanobelts and nanodisks in a transmission electron microscope by electron-beam irradiation of single-crystalline polyhedral Zn nanoparticles, which were synthesized by evaporating ZnO powder mixed with graphite in a N 2 flowing carrying gas environmen…
The carbon nanofibers used in this work were derived from polyacrylonitrile/N,N-dimethyl formamide precursor solution using electrospinning and vacuum pyrolysis techniques. Their conductivity σ was measured at temperatures between 1.9 and 300 K and transverse magnetic field between −9 and 9 T. Zero magnetic field cond…
The linear absorption spectra, resonance Raman excitation profiles and depolarization dispersion curves, and hyper-Rayleigh scattering profiles are calculated for excitonically coupled homodimers of a model electron donor–acceptor “push–pull” conjugated chromophore as a function of dimer geometry. The vibronic eigenst…
Abstract Blends of the conducting polymer, polypyrrole (PPy), and in the insulating host polymers, polyvinyl acetate (PVAc), polystyrene (PS), and polyvinyl chloride (PVC) resin, have been prepared chemically. Threshold conductivities occur at about 5% for PPy in blends with host polymers. The characterizations of the…
We present computer simulations of long, thin, hard spherocylinders in a narrow planar slit. We observe a transition from the isotropic to a nematic phase with quasi-long-range orientational order upon increasing the density. This phase transition is intrinsically two-dimensional and of the Kosterlitz–Thouless type. T…
We present a structural and magnetic study of La0.7Ca0.3MnO3 epitaxial films (the thickness ranges from 2.4 to 80 nm) on SrTiO3. Their structure, as obtained by x-ray diffraction, is orthorhombic with a 45° rotated 2×2 square lattice, referred to the SrTiO3 substrate, in the film plane. The 2.4 nm film adopts a differ…
The phase behavior of mixtures of polyisobutylene (PIB), polyethylene (PE), and a symmetric polyethylene- block -head-to-head polypropylene copolymer (PE−PP) was studied by transmission electron microscopy (TEM) and small-angle neutron and light scattering. The thermodynamic interactions between PE/PP and PE/PIB are r…
The low-field dielectric response of the relaxor-ferroelectric (1−x)PbFe2/3W1/3O3–xPbTiO3 ceramics with various x, was investigated. The permittivity data were analyzed with empirical laws that describe the diffuse phase transitions in relaxors. A change of the character of the phase transition was found with increasi…
A liquid crystal material of bent-core molecules is investigated by means of optical texture observations, x-ray measurements, and miscibility studies. While the x-ray and miscibility data point towards a B2 phase, the texture is however unusual, showing optical isotropy and segregation in two domains with opposite gy…
The thermal stability and dewetting effects of crystalline organic thin films on inorganic substrates have been investigated for a model system for organic epitaxy, 3,4,9,10-perylenetetracarboxylic dianhydride (PTCDA) on Ag(111). The thin films deposited under a variety of growth conditions have been annealed stepwise…
In this paper, we report the magnetic and electrical properties of the Te-doped lanthanum manganite perovskite compound ${\mathrm{La}}_{1\ensuremath{-}x}{\mathrm{Te}}_{x}{\mathrm{MnO}}_{3}$ and the related electron spin resonance (ESR) study. This is a material with rhombohedral structure and it shows good colossal ma…
Single-crystal nanoparticles of silicon, several tens of nm in diameter, may be suitable as building blocks for single-nanoparticle electronic devices. Previous studies of nanoparticles produced in low-pressure plasmas have demonstrated the synthesis nanocrystals of 2–10 nm diameter but larger particles were amorphous…
The symmetry of magnetic quantum tunneling has been studied in the prototype single molecule magnet Mn12-acetate using a micro-Hall effect magnetometer and superconducting high field vector magnet system. An average crystal fourfold symmetry is shown to be due to local molecular environments of twofold symmetry that a…
Abstract Rigid polyurethane foams (PUFs) were prepared from polymeric 4,4′‐diphenylmethane diisocyanate (PMDI), polyether polyol, 1,4‐butanediol, silicone surfactant, and distilled water. The properties of the synthesized PUF samples were investigated with differential scanning calorimetry, scanning electron microscop…
The photoluminescence of rutile and anatase TiO2 has been investigated in the range of 360–890 nm at several temperatures. An unexpected intense near-infrared (1.53 eV) photoluminescence band was recorded for both phases. At low temperatures, the resulting bands form a substructure of equally spaced peaks irrespective…