Materials Literature
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Germanium disulfide exhibits three solid forms: an amorphous form ($a$-Ge${\mathrm{S}}_{2}$), a layer-structure crystalline form (2D-Ge${\mathrm{S}}_{2}$), and a quartzlike crystalline form (3D-Ge${\mathrm{S}}_{2}$). We have carried out a series of experiments to determine the effect of pressure on the optical-absorpt…
We have measured the variation of the differential resistance as a function of the electric field for temperatures below those at which the two charge-density waves (CDW) form in Nb${\mathrm{Se}}_{3}$. The shape of the $\frac{\mathrm{dV}}{\mathrm{dI}}$ variation is very sensitive to temperature, particularly below tha…
We report a theoretical survey of defect energetics in $\ensuremath{\alpha}$-${\mathrm{Al}}_{2}$${\mathrm{O}}_{3}$ and rutile Ti${\mathrm{O}}_{2}$ which we relate to structural and transport properties of these materials. The study of these crystals has required us to modify our computational methods based on the Mott…
The photoelectronic properties of nominally pure SrTi${\mathrm{O}}_{3}$ single crystals were studied in detail. A sharp narrow peak near the fundamental absorption edge was observed in both photoconductivity and photoluminescence excitation spectra, although it was not detected in the absorption spectrum. The temperat…
The total energy for Si with various lattice distortions has been calculated using a first-principles linear-combination-of-atomic-orbitals method. The physical properties derived from these calculations include not only the equilibrium lattice constant, cohesive energy, and bulk modulus, but also the internal strain…
The room-temperature polarized reflectance of a potassium-deficient platinum chain salt ${\mathrm{K}}_{1.75}$Pt${(\mathrm{CN})}_{4}$\ifmmode\cdot\else\textperiodcentered\fi{}1.5${\mathrm{H}}_{2}$O [K(def)CP] has been measured in the infrared and visible. The reflectance is strongly anisotropic, with a plasma edge in t…
Crystalline powder pellets of MoO3 and WO3 were irradiated with 253.7 nm radiation at room temperature in vacuum, in the presence of H2 and in the presence of Hg vapor and H2. Electronic changes induced in the surface of the solids were studied by x-ray photoelectron spectroscopy. In vacuo both MoO3 and WO3 turned blu…
The structures of the paraelectric (tetragonal) phase of KH 2 PO 4 (KDP) and 95% deuterated KD 2 PO 4 (DKDP) have been investigated as a function of pressure and temperature using high-resolution (sin theta max / lambda >1 AA -1 ) single-crystal neutron-diffraction techniques. Data have been collected for both KDP and…
The structures of the paraelectric (tetragonal) phase of KH 2 PO 4 (KDP) and 95% deuterated KD 2 PO 4 (DKDP) have been investigated using high-resolution (sin theta b max / lambda >1.1 AA -1 ) single-crystal neutron-diffraction techniques. Full three-dimensional data have been collected at T c +5K and T c + approximat…
Some brown gem-quality diamonds exhibit bright yellow luminescence when excited with a long-wave ultraviolet (365 nm) mercury lamp. The authors describe detailed absorption and luminescence measurements in the visible spectral region, and absorption measurements in the defect-induced one-phonon region, using a large n…
Because the distances between atoms vary with direction within a crystal, the properties of a crystal also vary with direction. Such property variations are called crystalline anisotropy, and the amount of anisotropy depends on the symmetry of the crystal structure. The alpha-phases of uranium depends on the symmetry…
Abstract In measurements of grain boundary transport it is the product of the grain boundary enrichment ratio and the grain boundary diffusivity that is usually obtained. This work presents the first study in which these two terms are separated and in which the role of the grain boundary composition in grain boundary…
The commensurate charge-density-wave state of $2H$-${\mathrm{TaSe}}_{2}$ can have hexagonal ($H$) or orthorhombic ($O$) symmetry. With use of a Landau theory it is shown that near the boundary between $H$ and $O$ states a discommensuration splits into two $H\ensuremath{-}O$ interfaces and thereby greatly lowers its en…
一般式 (Bi2O2)2+(Mem-1RmO3m+1)2-で表されるBi層状化合物の中, 一致溶融し, しかも比較的高いキュリー点を有する7種の化合物の組成, 及びこれに少量のPbO, Bi2O3, B2O3などを添加した組成の融液を, 白金るつぼ中で70°-140℃/cmの温度こう配下で0.7-2.9mm/hの速度で下から上に向け一方向に凝固した. その結果, いずれの組成, いずれの凝固条件の場合も, 分極軸のa軸あるいはb軸を凝固進行方向にほぼ完全にそろえたBi層状化合物の配向性多結晶体が得られた. これらの多結晶体の多くは, 空げき及びき裂をいくらか含んでいたが, (Bi2O2)(PbNb2O7) にPbO-Bi2O3-B…
Fluoropolymers possess a number of unusual properties which should prompt wide usage in marine applications: (1) exceptional resistance to the effects of water, sunlight and biological organisms, (2) non-wetting, fast-draining surfaces, (3) anti-adhesive surfaces, (4) low friction or dry-film lubricant properties, and…
Abstract Experimental observations of the cyclic deformation and temperature rise in Mallory tubes during testing are described. The analyses of the data explain the temperature rise in terms of heat generated by the cord and rubber during the cyclic deformation. Using the measured temperature rise and the heat genera…
On the basis of structural data of the disordered tetragonal phase of tanane, the Van der Waals intermolecular forces are computed for the 16 nearest neighbours of a given molecule. Considering first the molecular ordering in a « rigid » tetragonal lattice, the pair energies between neighbouring molecules are analysed…
An investigation of two gear steels, AISI 9310 and VASCO X-2, carburized to a depth of 1.524 mm, was conducted to evaluate the effect of materials processing parameters on the fatigue lives of these materials in rolling contact fatigue, in single-tooth bending fatigue, and, finally, in a four-square dynamometer gear t…
Chemical and cation exchange characteristics, x-ray and DTA study of coarse and fine soil clays from duny areas of western Rajasthan showed that fine clays contained smectite, mica, mica-smectite and kaolinite. In addition to these, dune soil clay had minor amount of interlayered smectite and chloritic minerals, where…
Preliminary laboratory experiments were carried out to obtain some informatio on the nature of potential carbon fiber emissions resulting from the machining and incineration of graphite/epoxy composites. Examination of residues by scanning electron microscopy following exposure of graphite fiber products in a laborato…