Materials Literature
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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…
Cationic copolymerization of a functional aldehyde, methyl glyoxylate (GM), with a seven-membered cyclic acetal, 1,3-dioxepane (DXP), leads to polyacetals containing ester side groups that may be used for functionalization. Partial replacement of the ester groups in GM−DXP copolymers with amide groups by reaction with…
The solvoconductive properties of low-defect anodically coupled polypyrroles and polythiophenes, made so they are able to be solvated by organic vapors with suitable substituents, have been studied. The investigation was performed by contemporary conductivity and electrochemical quartz crystal microbalance analysis of…
Abstract Two new pyromellitic dianhydrides, 1,4‐bis(4′‐ t ‐butylphenyl) pyromellitic dianhydride and 1,4‐bis(4′‐trimethylsilylphenyl) pyromellitic dianhydride, were synthesized via Suzuki coupling, oxidation, and dehydration. A series of new organosoluble polyimides were prepared from the obtained pyromellitic dianhyd…
This study identifies surface chemistry characteristics based on competitive behavior in the simultaneous adsorption behavior of NOx (NO rich) and SO2 using KOH impregnated activated carbon (K-IAC) in excess O2. The NOx and SO2 adsorption on K-IAC occurred mainly through the acid-base reaction. The high surface area w…