Materials Literature
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Extensive characterization of the hole mobilities \ensuremath{\mu} in dispersions of p-diethylamino- benzaldehyde-diphenyl hydrazone (DEH) in polycarbonate has been carried out. We report the effect of varying the electric field E, temperature T, and spacing between DEH molecules \ensuremath{\rho} on \ensuremath{\mu}.…
X-ray photoelectron spectroscopy (the deconvoluted high-resolution N 1s core-level spectrum in particular) was used for the quantitative determination of the proportion of benzoid amine, quinoid imine, and protonated units in chemically synthesized polyaniline. This method allows the tracking of structural changes dur…
The near-infrared fluorescence of pure and doped KTaO 3 samples is studied. In the neighbourhood of 14570 cm -1 , 11 peaks are observed at 16 K and are associated with the fluorescence of a Ta 3+ ion near an O vacancy. In the ferroelectric KTa 0.982 Nb 0.0l8 O 3 crystal the fluorescence is not affected below T c appro…
The dynamics of the interface between an ordered phase, characterized by an order parameter, \ensuremath{\psi}, and a disordered phase where \ensuremath{\psi}=0 provide a promising, powerful tool to distinguish between continuous or second-order and weakly first-order phase transitions. We apply this idea to the nemat…
The stopping power for antiprotons has been measured for the first time. The antiproton stopping power of silicon is found to be 3%--19% lower than for equivelocity protons over the energy range 3.01 to 0.538 MeV. The ``${Z}_{1}^{3}$ contribution'' to the stopping power (the Barkas effect) is deduced by comparing the…
H2 and DH release was investigated in a pulsed deuterium discharge over a carbon thin-film deposited wall. A large quantity of hydrogen was desorbed by 300 eV D+2 irradiation from hydrogenated amorphous carbon (a-C:H) deposited by a hydrogen-admixed methane discharge. On the other hand, a strong pumping effect was obs…
We have found that encapsulated thin Si films, adjacent to SiO2, are dissolved at elevated temperatures by a reaction: Si+SiO2→2SiO, with SiO diffusing through the silica network. The presence of SiO in SiO2 in a concentration ≤3 at. % has a profound effect on thermomigration of dopant impurities in the oxide. We prop…
Two infrared local vibrational mode (LVM) absorption lines occurring at 715 and 845 cm−1 shift to 679 and 802 cm−1 in gallium arsenide doped with 18O, proving that the lines arise from the vibrations of oxygen impurities. The 715 cm−1 line exhibits a triplet 69,71Ga isotope fine structure consistent with that expected…
The solubility and the diffusion coefficient of hydrogen were determined in the austenitic (cubic) high-temperature phase of the shape-memory alloy NiTi. The measurements were made between 500 and 950 degrees C, with hydrogen gas pressures of up to 1.3 bar, and with hydrogen-to-NiTi ratios of up to 0.027. The hydrogen…
Abstract The method of matched asymptotic expansions is used to describe solutions of the nonlinear Cahn-Hilliard equation for phase separation in N > 1 space dimensions. The expansion is formally valid when the thickness of internal transition layers is small compared with the distance separating layers and wi…
Although the concept of an artificial photosynthetic reaction center that mimics natural electron-and energy-transfer processes is an old one, in recent years major advances have occurred. In this review, some relatively simple molecular dyads that mimic certain aspects of photosynthetic electron transfer and singlet…
Shape memory alloy (SMA) reinforced composites is a class of materials that have the ability to change their material properties, induce large internal distributed forces in a structure, can modify the stress and strain distribution within a structure, alter its geometric configuration, and do so all in a controlled m…
Interatomic potentials consisting of two-body and three-body covalent forces are proposed for ${\mathrm{GeSe}}_{2}$. Using these in molecular-dynamics simulations, the nature of intermediate-range order is investigated. All the features in S(q), including the first sharp diffraction peak (FSDP), are in agreement with…
We have used time-resolved digital imaging of uniform, charged polystyrene spheres in colloidal suspension confined between smooth glass plates to study in detail the nature of particle motions in equilibrated two-dimensional dense fluid, hexatic, and crystalline phases. We observe dynamic ordered regions in the fluid…
For pt.I see ibid., vol.1, p.2341 (1989). The electrical resistivity and the Hall effect of inter-metallic compounds XMnSb (X=Pt, Ni, Au) and PtMnSn were investigated in the temperature region 4-1000 K. The results for the anomalous Hall effect were analysed in terms of skew scattering and side-jump contributions. Thi…
The authors present investigations of the crystal structure the microstructure and the magnetic properties of the inter-metallic compounds XMnSb (X=Pt, Ni, Co, Au, Cu) and PtMnSn. It was found that several of these materials contain precipitates of other phases and/or large atomic disorder, which can be influenced by…
We report results of degenerate four-wave mixing measurements of nonresonant nonlinearities in a variety of high-index lead and bismuth containing oxide glasses and the chalcogenide As2S3. The third-order nonlinear susceptibilities of the oxide glasses are found to scale with the heavy metal content. A lead-bismuth-ga…
The substitution of Mg into cement clinker phases has been studied by isothermal annealing, followed by X-ray diffraction, electron microscopy and analysis and infrared spectroscopy of the products. The substitution of Mg into 12CaO.7Al 2 O 3 is slight, and is not enhanced by concomitant substitution of fluorine. Howe…
A hot extrusion method was utilized to develop Nd-Fe-B permanent magnets suitable for radial or circumferential applications, such as in stepping motors. Billets produced by hot-pressing rapidly quenched powder were subjected to extrusion. A plane-anisotro-pic magnet was obtained by forward extrusion, and a radially a…
Experiments have been carried out to study the influence of hydrogen on the mechanical properties of a stable 304 stainless steel by using a procedure for hydrogen charging which did not cause the irreversible damage of the steel which invariably accompanies electrolytic charging. The effect of hydrogen on the mechani…