Materials Literature
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The crystal structure of triclinic potassium dichromate has been determined by single crystal X-ray diffraction. The cell constants are a = 13.367, b = 7.376, c = 7.445 Å, α = 90.75°, β = 96.21°, γ = 97.96° with four K 2 Cr 2 O 7 units per cell. Refinement of 2600 reflections in both the space groups P1 and [Formula:…
The optical reflectance of Co has been measured in the spectral range $0.05 \mathrm{eV}\ensuremath{\le}h\ensuremath{\nu}\ensuremath{\le}11.8 \mathrm{eV}$. The reflectance is low and decreases monotonically in the region $h\ensuremath{\nu}\ensuremath{\ge}0.05$ eV, indicating that strong absorption has started at photon…
A number of compositions [Formula: see text] and of related mixed phases were prepared and investigated. For the trivalent lanthanons from La to Lu, and for Y, the homogeneous A 2 Sn 2 O 7 phases were of the cubic pyrochlore type (space group Fd3m, No. 227). Their lattice parameters gave a very good linear relationshi…
Paramagnetic CuMoO4 is triclinic, space group P1̄, with lattice constants a = 9.903 ± 0.028, b = 6.783 ± 0.015, c = 8.359 ± 0.0019 Å, α = 101.08° ± 0.20°, β = 96.88° ± 0.20°, and γ = 107.05° ± 0.20° at 298°K, with six formula weights in the unit cell. The integrated intensities of 6310 reflections within a reciprocal…
Transmission spectra of sublimed thin films of the α-crystalline forms of H2PC, CuPC, NiPC, CoPC, and ZnPC in the 0.5 to 0.9-μ region changed sharply as a result of α→β transformation induced by heat treatment above 300°C. The VOPC was unaffected. In the β-crystalline forms the absorption maxima (cm−1) were: H2PC 13 9…
Gold-rich (73–81 at.% Au) alloys of gold–germanium–silicon were “splat” cooled to an amorphous solid form. Thermal and rheological evidence of a glass-liquid transition in the Au0.77Ge0.136Si0.094 alloy is reported. The transition was manifested thermally by an abrupt rise of 5.5 cal/g-atom·°K in specific heat, Cp, as…
Results are presented of measurements of the thermal conductivity (90-1328\ifmmode^\circ\else\textdegree\fi{}K), the electrical resistivity (300-1273\ifmmode^\circ\else\textdegree\fi{}K), and the Seebeck coefficient (350-1273\ifmmode^\circ\else\textdegree\fi{}K) for single-crystal and large-grained polycrystalline spe…
An analysis is presented of the compatible subgroups which can arise by second-order phase transition from the perovskite structure, without change of unit cell. The symmetry analysis is based upon the subduction-criterion simplification of the thermodynamic Landau theory. The possible displacements from the perovskit…
Measurements at room temperature of the infrared reflectivity of oriented samples of orthorhombic NaN${\mathrm{O}}_{2}$ crystals have been carried out and analyzed by Kramers-Kronig relations to obtain the principal dielectric response functions. The eight infrared dispersion frequencies found are well accounted for b…
The temperature dependences of the hyperfine magnetic fields at ${\mathrm{Fe}}^{57}$ nuclei in $A$ and $B$ sites of ${\mathrm{Fe}}_{3}$${\mathrm{O}}_{4}$ have been determined with the M\"ossbauer-effect technique. A comparison with neutron diffraction data shows that the ${H}_{\mathrm{hpf}}$-versus-$T$ curves follow t…
The low-lying phonon and magnetic excitations of CoO have been studied experimentally and theoretically, both above and below the antiferromagnetic ordering temperature. The experiments were performed using the technique of inelastic scattering of slow neutrons with the aid of a triple-axis crystal spectrometer. These…
A gallstone of almost perfect octahedral symmetry was composed of a mixture of crystallites of the three polymorphous forms of calcium carbonate: calcite, aragonite, and vaterite.
Abstract The low polymerization of ethylene oxide with sodium dimethyldithiocarbamate in a homogeneous system was studied. This reaction was verified as proceeding through a step-by-step addition mechanism, due to the enhanced nucleophilicity of the dithiocarbamate anion in dipolar aprotic solvents. The solvent effect…
A method has been developed for obtaining lattice spacings of powder samples by x-ray diffraction in times potentially as short as 1 second. The sample is irradiated with polychromatic radiation from an x-ray tube, and the energy spectrum of x-rays scattered at a given angle is observed with a semiconductor radiation…
Abstract The self-diffusion coefficient of ions or atoms in such crystals as halides, oxides and sulfides can be determined from the rate of the diffusion-controlled solid-state reaction as well as by the tracer method. In the present study, the self-diffusion coefficient of nickel atoms in nickel sulfide was determin…
An account is given of an investigation of the effects of fibre type (rayon, acrylic fibre, wool, and cotton) and dimensions on the properties of needled fabrics, the test methods used being those described in a previous paper. Some fabrics show a stick-slip behaviour in extension; others deform smoothly. Rayon webs c…
The reaction kinetics of graphite with hydrogen at high temperatures and pressures was studied by measuring the rate of weight loss and surface recession of graphite samples. Under experimental conditions, methane and acetylene were the predominant products. From previous studies, surface reaction mechanisms were assu…
Abstract The solubility of cellulose triacetate in a range of solvents was measured, and the results for tetrachloroethane, chloroform, and acetic acid were compared with those from initial phase separation in solvent–nonsolvent mixtures and viscosity–concentration studies. The correlation found between solubilities,…
Vaporization experiments with liquid samples of TiO, Ti3O5, Ti4O7, Ti5O9, and TiO2 were performed, and the residues were analyzed by x-ray diffraction procedures. The results show that the congruently vaporizing composition lies between the composition Ti3O5 and the composition Ti4O7 instead of at the composition Ti3O…
Axisymmetric plastic buckling of axially compressed cylindrical shells is studied for semi-infinite shells and shells of finite length subject to free-edge boundary conditions. It is shown that the length of the cylinder has a negligible effect on the buckling load. Reductions in buckling stresses from the classical s…