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。
Within the framework of a partial-density approach, the confinement of vibrations in spherical Si nanocrystals is studied and the Raman frequency shifts of Si spheres with different sizes are derived based on the Raman spectra obtained by a bond-polarizability model. The results obtained by the bond-polarizability mod…
The attributes of electron field emission from disordered matrix arrays of carbon nanotubes are studied and found to be quite reproducible in spite of the disorder, density, and quality variations from sample to sample. At low applied electric fields, the electron field emission current-voltage characteristics qualita…
In the substitutionally disordered narrow-gap semiconductor Pb_{1-x}Ge_xTe, a finite-temperature cubic-rhombohedral transition appears above a critical concentration $x \approx 0.005$. As a first step towards a first-principles investigation of this transition in the disordered system, a (hypothetical) ordered cubic P…
We apply ab initio quantum chemical methods to calculate correlation effects on cohesive properties of NiO, thereby extending a recently proposed scheme to transition-metal oxides with partially filled d bands. We obtain good agreement with experiment for the cohesive energy and show that the deviation of the lattice…
The bare and hydrogen-covered diamond (100) surfaces were investigated through pseudopotential density-functional calculations within the local-density approximation. Different hydrogen coverages, ranging from one to two, were considered. These corresponded to different structures (1\ifmmode\times\else\texttimes\fi{}1…
A “colossal” negative magnetoresistance (CMR) occurs in manganites at a first-order ferromagnetic transition. The Mn4+ and high-spin Mn3+ ions each contain localized t3 configurations; the t3–pπ–t3 superexchange interactions are antiferromagnetic. The orbital degeneracy of localized Mn3+:t3e1, Eg5 configurations is li…
The exciton-phonon coupling strength of PbS nanocrystals that strongly confine both charge carriers is investigated using resonant Raman scattering. The strength of this coupling (Huang-Rhys parameter S\ensuremath{\sim}0.7) is four orders of magnitude greater than that predicted theoretically for the intrinsic states…
Anomalous magnetic properties of organic coated NiFe2O4 nanoparticles have been reported previously (Berkowitz et al.).5 These properties included low magnetization with a large differential susceptibility at high fields and shifted hysteresis loops after field cooling, while Mössbauer spectra indicated that all of th…
The oxidation of liquid-gallium surfaces has been investigated with surface x-ray scattering techniques. By exposing the liquid-metal surface at room temperature to doses on the order of 180 L of oxygen where 1 L=${10}^{\mathrm{\ensuremath{-}}6}$ Torr s, a gallium oxide film with a well-defined thickness of \ensuremat…
The changes in density, wave functions, and self-consistent potentials of solids, in response to small atomic displacements or infinitesimal homogeneous electric fields, are considered in the framework of the density-functional theory. A variational principle for second-order derivatives of the energy provides a basis…
Abstract Mercury is known to be present as a trace component in many natural gas reservoirs. As an environmentally hazardous element, mercury has to be removed from the gas stream, preferably on the production site. This removal causes various problems for the operator. First of all the selection of adequate analytica…
There is a quite serious discrepancy in the literature, in the electron energy range 5 - 10 eV, between the most recent elastic differential cross section (DCS) measurements of Woeste et al and Sullivan et al , particularly for electron scattering angles of less than . This disagreement is reflected in both the shape…
The magnetization of F- and P-type icosahedral Al - Pd - Mn was studied in the temperature region between 2 and 870 K in a magnetic field below 80 kOe. F-type icosahedral phase samples obtained by quenching from 1075 K were transformed to the low-temperature-phase form during the magnetic measurement above 600 K. The…
A novel layer-by-layer cubic growth pathway involving ${\mathrm{C}}_{2}$ dimers is advanced for large titanium carbide clusters based on observation of new magic numbers in the anions. This growth mechanism explains uniquely all the magic numbers in a multicage growth model previously proposed for large metal carbide…
Dielectric spectroscopy up to a frequency of 380 GHz has been performed on the molten salts $[\mathrm{Ca}({\mathrm{NO}}_{3}{)}_{2}{]}_{0.4}[{\mathrm{KNO}}_{3}{]}_{0.6}$ (CKN) and $[\mathrm{Ca}({\mathrm{NO}}_{3}{)}_{2}{]}_{0.4}[{\mathrm{RbNO}}_{3}{]}_{0.6}$ (CRN). For the first time, conclusive results for the transiti…
We report the effect of both miscut angle (α) and miscut direction (β) of vicinal substrates on the epitaxial growth and domain structure of isotropic metallic oxide SrRuO3 thin films. The thin films have been grown on vicinal (001) SrTiO3 substrates with α up to 4.1° and β up to 37° away from the in-plane [010] axis.…
The vibrational modes of the sp3 sites in tetrahedral amorphous carbon (ta-C) thin films are revealed directly using ultraviolet Raman spectroscopy at 244 nm excitation and are shown to produce a Raman peak centered around 1100 cm−1. In addition, the main Raman peak associated with sp2 vibrational modes is shifted upw…
Blends of poly(vinyl chloride) (PVC) and acrylonitrile-chlorinated polyethylene-styrene (ACS) graft copolymer were prepared by melt blending. Mechanical properties were studied by the use of dynamic mechanical analysis (DMA), impact tests, tensile tests, and scanning electron microscopy (SEM). The DMA study showed tha…
Inclusion compounds (ICs) can be formed between small-molecule hosts and guest polymers, where the crystalline host lattice confines the guest polymers to occupy narrow cylindrical channels. The included polymers are highly extended by the narrow channel diameters and are separated from neighboring polymer chains by t…
In vitro degradation of poly(L-lactic acid) fibers was investigated for a period of 16 weeks in Ringer solution at 37°C. Two sets of fibers, with similar initial mechanical properties, molar mass, and crystallinity content, but markedly different in diameter (72 and 120 μm) were studied. Viscometric molar mass decreas…