Materials Literature
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With use of an electronic picture-scanning device and a digital computer, electron micrographs taken of a specimen along several different directions can be superimposed to form a montage that is more informative than the component images. Preliminary results indicate that one may thus study unstained, unshadowed biol…
Radiative corrections to bremsstrahlung and pair-production cross sections have been detected experimentally by measuring the thin-target bremsstrahlung spectrum of 5-GeV electrons with a pair spectrometer. Deviations of up to 5% from lowest-order calculations have been observed and found to agree with predictions for…
Through control of the crystallization process many polymers can be made to exhibit a broad spectrum of structural possibilities, ranging from a state of high disorder to one of high order. Emphasis has been placed on bulk-crystallized polymers which normally fall near the center of this spectrum. This was done in par…
Abstract Durch Streulichtmessungen werden an Acetonlösungen von zwei Reihen fraktionierter Cellulosetrinitrate (CTN 13,9 und CTN 12,9 entsprechend dem %‐Gehalt N) Molekulargewicht, Trägheitsradius r̄ und 2. osmotischer Virialkoeffizient A 2 gemessen. Der Expansionskoeffizient gehorcht der Gleichung α 5 − α 3 = 2,6 z.…
We have determined the phase diagram for the notrogen–oxygen system by examining the x-ray diffraction patterns of polycrystalline samples of the solidified mixtures over the temperature range 21°–50°K. The diagram exhibits a surprising complexity: a eutectic line divides the liquid and the two-phase region of (γ-O2 +…
Ultrasonic absorption and velocity have been measured in anhydrous N,N-dimethylformamide solutions of hydrogen chloride, over the frequency range 13 to 143 mc/s, and the concentration range 0.05 M to 3.5 M. A large relaxation is observed and ascribed to the association of the acid. The rate constants for this reaction…
The thermal conductivity and the specific heat of RbCl containing RbCN in concentrations between ${10}^{17}$ and ${10}^{19}$ ${\mathrm{cm}}^{\ensuremath{-}3}$ in solid solution has been measured above 0.05\ifmmode^\circ\else\textdegree\fi{}K. Resonance scattering of phonons is found in the thermal conductivity around…
The nature of the atomic arrangement in the phase of AgI existing at pressures between 3 and 4 kbar has been deduced from x-ray diffraction studies with a diamond-anvil apparatus. The unit cell is either tetragonal or pseudotetragonal and contains a total of 4 atoms at 000, 12120, 120z, 012z̄ with z = 0.3. The calcula…
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.