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。
Atom positions and anisotropic Debye-Waller factors of the rhombohedral phase of LaCrO(3) have been refined simultaneously with the low-order structure factors, using a structure-analysis method of convergent-beam electron diffraction (CBED) proposed by Tsuda & Tanaka [Acta Cryst. (1999), A55, 939-954]. The method is…
High-resolution x-ray rocking diffraction has been used to measure the spontaneous strain associated with the cubic–rhombohedral phase transition in LaAlO 3 in the range 10K ≤ T ≤ 750 K. The data are consistent with a second-order Landau-like model at high temperatures, with T C = 834(2) K. At lower temperatures, the…
Calcium doping levels of up to 20 % can be achieved for the La1−xCaxOCl1−x solid solution series. At the highest doping levels (x=0.2; see graph (•)), the conductivity of the solid solution is three orders of magnitude greater than that of undoped LaOCl (□). The potential for the design of new functional materials ste…
Trinuclear copper complexes have been obtained by using a 1,3,5-trihydroxybenzene ligand modified by attachment of pendant arms at the 2, 4, and 6 positions (see picture; XX=bipyridine, 2-formylphenolate). The m-phenylene linkage results in ferromagnetic interactions through spin polarization in these complexes.
An almost spherical cluster with a diameter of about 2.5 nm is formed by Ag atoms (blue), S2− ligands (yellow), and P atoms (green) of PnPr3 ligands in [Ag188S94(PnPr3)30] (see picture). The phosphane ligands from the spherical Ag2S cluster core point out like the spines of a hedgehog. The sulfur substructure is const…
Oriented by an electric field (but not otherwise), a lyotropic nematic phase of helical discotic 1 in dodecane exhibits second-harmonic generation, the intensity of which is affected by the helicity of the irradiating circularly polarized light. The change reverses sign when the polarity of the orienting electric fiel…
Three electrons can be accepted into the antibonding orbitals of the α,α′-{2,6-(iPr)2PhNC(Me)}2(C5H3N) ligand, so that reduction with [Li(naphthalenide)] yields the trianionic diamagnetic complex 2. Treatment with Li metal, a stronger reducing agent, gives a mixture of 2 and paramagnetic complex 1, which is thermally…
Tuned chemical conditions complemented with a set of treatments have been developed to enhance the thermal stability of transition metal oxide mesoporous thin films (up to 500 °C for TiO2 and 450 °C for ZrO2), allowing the formation of crack-free coatings presenting excellent optical quality (transmittance higher than…
Water-soluble species can be deposited into preformed, multilayered polyelectrolyte capsules, templated onto melamine formaldehyde particles, with high integrity. Efficient encapsulation of albumin within capsules formed from a poly(styrene sulfonate)/poly(allylamine hydrochloride) composite was achieved at pH values…
By means of the nonequilibrium Green function technique, the effect of spin-flip scatterings on the spin-dependent electrical transport in ferromagnet-insulator-ferromagnet (FM-I-FM) tunnel junctions is investigated. It is shown that Julliere's formula for the tunnel conductance must be modified when including the con…
The field-induced transition in one-dimensional S=1 Heisenberg antiferromagnet with single-ion anisotropy in the presence of a transverse magnetic field is obtained on the basis of the Schwinger boson mean-field theory. The behaviors of the specific heat and susceptibility as functions of temperature as well as the ap…
The effect of nonmagnetic impurities and the effective masses on the spin-dependent transport in a ferromagnet-normal metal-ferromagnet junction is investigated on the basis of a two-band model. Our results show that impurities and the effective masses of electrons in two ferromagnetic electrodes have remarkable effec…
We report a theoretical analysis of the phonon thermal conductance, κ(T), for single wall carbon nanotubes (SWCN). In a range of low temperatues up to 100K, κ(T) of perfect SWCN is found to increase with temperature, approximately, in a parabolic fashion. This is qualitatively consistent with recent experimental measu…
Elevated temperature STM measurements have shown that one key phase during gas-source homoepitaxy of Si(001) is the formation of clean Si ad-dimers from hydrogenated ad-dimers, though the mechanism for this formation is unknown. We present ab initio density functional calculations designed to explore this mechanism. T…
Quantum fluctuations of some systems vanish not only in the limit $\hbar\to 0$, but also as some other parameters (such as $1\over N$, the inverse of the number of `colors' of a Yang-Mills theory) vanish. These lead to new classical limits that are often much better approximations to the quantum theory. We describe tw…
Rhombohedral B4C coatings were synthesised on fused silica substrates by CO2 laser-assisted chemical vapour deposition (LCVD), using a dynamic reactive atmosphere of BCl3, C2H4 and H2. Films with carbon content from 15 to 22 at.% were grown at deposition rates as high as 0.12 micrometers per second. The kinetics of th…
Boron carbide thin films were synthesised by laser-assisted chemical vapour deposition (LCVD), using a CO2 laser beam and boron trichloride and methane as precursors. Boron and carbon contents were measured by electron probe microanalysis (EPMA). Microstructural analysis was carried out by Raman microspectroscopy and…
The Neutron Residual Stress Facility (NRSF) at ORNL's High Flux Isotope Reactor (HFIR) is being significantly upgraded in conjunction with the upgrade of the HFIR and associated neutron scattering facilities. We have rewritten the LabVIEW-based data acquisition and control software for the NRSF to provide much greater…
This paper focuses on the synthesis of rhombohedral B4C (r-B4C) coatings by CO2 laser-assisted chemical vapour deposition (LCVD), using a dynamic reactive atmosphere of BCl3, H2 and CH4 or C2H4. The influence of the carbon precursor on the deposition kinetics is discussed. The use of ethylene as carbon precursor prese…
There is a widely-held belief that the preparation of new solid-state compounds based on rational design is not possible. Herein, we present a concept that points the way towards a rational design of syntheses in solid-state chemistry. The foundation of our approach is the representation of the whole material world, t…