Materials Literature
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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…
A triblock copolymer template and an organosiloxane or organic additive facilitated the first synthesis of large-pore (up to 9.5 nm) three-dimensional bicontinuous mesoporous silica with Ia3d-type symmetry at room temperature in acidic medium. The picture is a transmission electron micrograph showing the pores along […
High resolution neutron powder diffraction and single crystal measurements on the ferromagnetic shape memory compound Ni 2 MnGa have been carried out. They enabled the sequence of transformations which take place when the unstressed, stoichiometric compound is cooled from 400 to 20 K to be established. For the first t…
Silaffins are uniquely modified peptides that have been implicated in the biogenesis of diatom biosilica. A method that avoids the harsh anhydrous hydrogen fluoride treatment commonly used to dissolve biosilica allows the extraction of silaffins in their native state. The native silaffins carry further posttranslation…
In this work, benzoyl peroxide is used as an oxidizing agent to oxidize aniline to polyaniline salt in the presence of protic acids such as sulfuric or nitric acid. The polymer samples are characterized by infrared, X-ray diffraction, particle size, resistance and density measurements. Polyaniline salts are used as ca…
Abstract The glass transition temperature ( T g ), crystallization, and melting character of a class of random polyester ionomers (polymer containing < 10 mol % ionic groups) were investigated. The nonlinear change of the T g and crystallization and melting behavior were characterized using differential scanning co…
Reciprocal lattice mapping has been performed on Fe0.81Ga0.19 crystals by ω–ω/2θ, Ψ–φ, and ω–φ scans. A strong elongation of the 〈001〉c peak was found along the 〈110〉c direction. ω scans revealed short lateral correlation lengths ξ along 〈110〉c and strong diffuse scattering along the 〈001〉c. Multiple domains with mono…
Abstract The effects of the block length and block number of linear styrene–butadiene (S–B) block copolymers on their compatibilization efficiency in blending polystyrene with polybutadiene were studied. For this purpose, two sets of model S–B copolymers and both homopolymers were prepared by anionic polymerization. D…