Materials Literature
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Single crystals of a continuous series of MnAs1-xSbx solid solutions are obtained and their crystal structure and magnetic properties are investigated in the temperature range from 150 to 600 K. It is shown that the crystal structure of MnAs, MnSb, and alloys with a small content of Sb and As, respectively, is charact…
The possibility of using the vascular endothelial cell as a target for gene replacement therapy was explored. Recombinant retroviruses were used to transduce the lacZ gene into endothelial cells harvested from mongrel dogs. Prosthetic vascular grafts seeded with the genetically modified cells were implanted as carotid…
Excitonic states in pure and anion-impurity-doped MgO are investigated in several well-defined models using unrestricted Hartree-Fock (UHF)/icecap (ionic crystal with electronic cluster, automatic program) simulation procedures. The calculated excitation energies in pure MgO are in excellent agreement with the experim…
SnHfS 3, M r = 393.36, orthorhombic, Pnma, a=9.139(1), b=3.694(1), c--13.875(4) A, V= 468.4 (2) ,/k 3, Z = 4, D x = 5.578 g cm 3, 2(Mo Kii) = 0.71073 ,~, g= 284.1 cm -~, F(000) 680, T= 298 K, R r=0.036 for 1301 observed reflections with I >_ 2.5tr(I). PbHfS 3, Mr = 481.88, orthorhombic, Pnma, a = 8.988 (2), b = 3-7…
Low-temperature annealing of the cleaved Si(111)2\ifmmode\times\else\texttimes\fi{}1 surface revealed the existence of an intrinsic 5\ifmmode\times\else\texttimes\fi{}5 reconstruction on the clean Si(111) surface. The electronic structure of the Si(111)5\ifmmode\times\else\texttimes\fi{}5 surface, obtained with angle-…
Na 8 (Al 6 Ge 6 O 24 )Cl 2 cristallise dans P43n avec affinement jusqu'a 0,013. Na 8 (Al 6 Ge 6 O 24 )Br 2 cristallise dans P43n avec affinement jusqu'a 0,019. Na 8 (Al 6 Ge 6 O 24 )I 2 cristallise dans P43n avec affinement jusqu'a 0,016
The photoelectron and Auger spectra of SiF4 have been measured, using synchrotron radiation in the 100 to 125 eV photon energy range in the vicinity of the Si2p ionization threshold. Partial photoionization cross sections have been obtained for outer, inner valence states and satellite states in the same energy range,…
Interface reactions of adatoms of Y, Ba, Cu, and Ti with ordered and disordered SrTiO3 (100) surfaces were examined with x-ray photoemission spectroscopy, Auger spectroscopy, and low-energy electron diffraction. Atomic distributions for these interfaces before and after annealing at 500 °C were determined using Ar ion…
ZnO has been doped with various oxides, mainly bismuth, cobalt, and manganese oxides. The aim of the present approach is to look at the influence of each dopant on the electrical behavior of ZnO in a system which is more simple and chemically purer in comparison with commercial varistors. It appears that cobalt or man…
Real surfaces are rough and chemically heterogeneous on many length scales and wetting phenomena on these surfaces are affected by this inhomogeneous nature. We have used x-ray reflectivity to examine the structure of static precursing films which precede the macroscopic meniscus of water on glass. We have examined th…
Results of self-consistent ab initio band-structure calculations using the augmented--spherical-wave method are presented for the stable intermetallic compounds ${\mathrm{Y}}_{2}$${\mathrm{Fe}}_{17}$, ${\mathrm{Y}}_{6}$${\mathrm{Fe}}_{23}$, ${\mathrm{YFe}}_{3}$, and ${\mathrm{YFe}}_{2}$ and for the hypothetical compou…
The diffraction by two planar slanted fringe gratings superposed in the same volume of an anisotropic medium is treated using rigorous 3-D vector coupled wave analysis. Arbitrary angle of incidence and polarization are included. Both phase and/or amplitude slanted gratings in anisotropic media are treated in the analy…
Preliminary studies were conducted on the laser processing of SiC/A356-Al alloy metal matrix composite (MMC) for such applications as welding/joining and cutting. The SiC/A356-Al MMC was processed using several different laser specific energies. Microstructural observations after laser processing revealed that the ext…
The oxygen-carbon luminescence defects with no-phonon emission at 0.767 eV (``P line'') and 0.79 eV (``C line'') created in pulled silicon after 450 \ifmmode^\circ\else\textdegree\fi{}C thermal annealing or electron irradiation, respectively, are investigated in a comparative study. This includes investigation of all…
Alloys with the composition RE2Fe17 and RE2Fe15X2 (X=Al,Ga) have been synthesized by the arc-melting technique followed by an 125-h anneal at 900–1000 °C in evacuated silica capsules. The new compound Nd2Fe15Ga2 is unstable below 800 °C, and is only obtained by quenching from above 900 °C. From x-ray powder diffractio…
We present for the first time a comparative vibrational study of polythiophene, polypyrrole, and polyisothianaphthene. The calculation is performed at k=0 in the plane of the chains for both aromatic-like and quinoid-like structures. The Ag species which are present in the Raman spectra are more particularly investiga…
Pseudomorphic Si/Si-Ge strained layer superlattices are metastable and will relax to lower-energy, less strained, states on thermal annealing. Such relaxation may occur by the generation of misfit dislocation or by compositional homogenization of the superlattice. The particular mechanism adopted is shown to depend on…
We calculate the contribution to the thermal conductivity, \ensuremath{\kappa}, in amorphous solids of the hopping of localized vibrational modes coupled to phonons via the anharmonic interaction. This contribution is generally important for temperatures above the plateau region in \ensuremath{\kappa}. The temperature…
Point defects, impurities, and defect-impurity complexes in diamond particles and polycrystalline films were investigated by cathodoluminescence (CL) imaging and spectroscopy in a scanning electron microscope. The diamond films and particles were grown by hot-filament methane-hydrogen chemical-vapor deposition at seve…
A high density of microvoids could cause inhomogeneous distribution of deep localized states in amorphous germanium. The electronic transport in such media is no longer dominated by Mott variable-range hopping. The dc conductivity is proportional to ${T}^{n}$ with n\ensuremath{\simeq}6, suggesting that the transport i…