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。
The statistical mechanical ensemble associated with molecular-dynamics (MD) simulations with the weak coupling (WC) thermostat proposed by Berendsen et al. [J. Chem. Phys. 81, 3684 (1984)] is analyzed. Using a generalized Liouville equation, an approximate equilibrium distribution function in the configurational space…
C−H bond activations of benzene and methane by M( η 2 -O 2 CH) 2 (M = Pd or Pt) are theoretically investigated with density functional theory (DFT), MP2-MP4(SDQ), and CCSD(T) methods. The C−H bond activation of benzene takes place with activation energies ( E a ) of 16.1 and 21.2 kcal/mol and reaction energies (Δ E )…
Ozone is a unique species whose chemistry has a profound impact in many areas of our society. It is well known as a beneficial constituent of the upper atmosphere which shields living organisms fro...
Stereochemistry can be said to have begun in 1848 when Pasteur observed that crystals of sodium ammonium tartrate obtained by slow recrystallisation at room temperature were of two mirror image crystallographic forms. He was able to pick out these two forms by hand and show that solutions of equal concentration caused…
A peculiar peak structure is observed in the optical absorption edge of β-Ga2O3 at low temperature. These peaks appear in an energy range corresponding to the excitation of the acceptor defects. It is suggested that some of these acceptors be assembled in low dimensional clusters with size about 30–40 Å and forming po…
Structure, mechanical properties, and sintering of nanostructured SiC (n-SiC) are investigated with neutron scattering and molecular-dynamics (MD) techniques. Both MD and the experiment indicate the onset of sintering around 1500 K. During sintering, the pores shrink while maintaining their morphology: the fractal dim…
Dislocation plasticity in a thin Cu film on a SiNx/SiOx coated silicon wafer was observed by transmission electron microscopy (TEM) during thermal cycling of a cross-sectional specimen. While the in situ TEM study revealed jerky dislocation motion at low homologous temperatures, continuous dislocation glide occurred a…
Motivated by recent neutron, x-ray absorption, and resonant scattering experiments, we revisit the electronic structure of ${\mathrm{V}}_{2}{\mathrm{O}}_{3}$. We propose a model in which $S\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}1$ ${\mathrm{V}}^{3+}$ ions are coupled in the vertical V-V pairs forming twofo…
The layer compression modulus was measured near the smectic- A-smectic- C(*)(alpha) phase transition in a chiral smectic liquid crystal. The layer compression modulus B shows marked pretransitional effects above the phase transition. The critical softening of B can be fit to a simple power law. It is described by the…
Spectroscopic ellipsometry over the photon energy 1.5–5.0 eV is used to derive the dielectric function of V2O5 nanocrystalline films deposited by plasma-enhanced chemical vapor deposition. The dispersion in the optical response is described by a combination of Lorentzian oscillators. The results are obtained from a mi…
In situ high-temperature, high resolution transmission electron microscopy (HRTEM) was performed on an Al-Cu-Co decagonal quasicrystal, to investigate thermal fluctuation of phasons. A tiling pattern constructed from the HRTEM image was analyzed in the framework of the strip-projection method. Transitions between two…
We report a systematic study of the microstructure and dielectric properties of barium strontium titanate, Ba1−xSrxTiO3, films grown by laser ablation on LaAlO3 substrates, where x=0.1–0.9 at an interval of 0.1. X-ray diffraction analysis shows that when x<0.4, the longest unit-cell axis is parallel to the plan…
A grain-size-dependent reduction in the room-temperature thermal conductivity of nanocrystalline yttria-stabilized zirconia is reported for the first time. Films were grown by metal-organic chemical vapor deposition with controlled grain sizes from 10 to 100 nm. For grain sizes smaller than approximately 30 nm, a subs…
The first measurements of the tensile elastic modulus of polypyrrole nanotubes are presented. The nanotubes were mechanically tested in three points bending using atomic force microscopy. The elastic tensile modulus was deduced from force-curve measurements on different nanotubes with outer diameter ranging between 35…
Using one- and two-dimensional NMR spectroscopy applied to 13C spin-labeled (TMTTF)2AsF6 and (TMTTF)2PF6, we demonstrate the existence of an intermediate charge-ordered phase in the TMTTF family of charge-transfer salts. At ambient temperature, the spectra are characteristic of nuclei in equivalent molecules. Below a…
The electronic structure of Ge nanocrystals is studied using a sp3 tight binding description. Analytical laws for the confinement energies, valid over the whole range of sizes, are derived. We validate our results with ab initio calculations in the local density approximation for smaller clusters. Comparing to experim…
The effect of oxygenation on the electronic properties of semiconducting carbon nanotubes is studied from first principles. The O2 is found to bind to a single-walled nanotube with an adsorption energy of about 0.25 eV and to dope semiconducting nanotubes with hole carriers. Weak hybridization between carbon and oxyge…
The high-temperature (beta-) modification of Hg2MoO4 was prepared by solid-state reaction of HgO with MoO2 at 400 degrees C. Well-crystallized samples of the low-temperature (alpha-) modification of Hg2MoO4 and isotypic Hg2WO4 were obtained by hydrothermal recrystallization of the microcrystalline powders at 180 degre…
Spicule matrix proteins are the products of primary mesenchyme cells, and are present in calcite spicules of the sea urchin embryo. To study their possible roles in skeletal morphogenesis, monoclonal antibodies against SM50, SM30 and another spicule matrix protein (29 kDa) were obtained. The distribution of these prot…
Electron paramagnetic resonance (EPR) spectroscopy was used to investigate adsorption of a series of amines (ammonia, methylamine, triethylamine) on Cu−ZSM5 and Cu−Beta. Several changes were observed in the EPR spectra after adsorption of the amine: an increase in spectral broadening, a shift in the copper hyperfine f…