Materials Literature
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The new interpolation procedure of Shankland is applied to interpolation problems found in a periodic lattice. Two problems, the method of averaging the valence electron density over the Brillouin zone and the method of interpolating energy bands throughout the Brillouin zone from values at symmetry points, are discus…
A method is presented for calculating anharmonic contributions to the Debye-Waller factor in the high-temperature limit in terms of direct-space sums. These sums are simpler quantities than those resulting from the phonon technique, in that there are no multiple integrals in reciprocal space and the frequencies and po…
The effects of strain on optical critical-point structure in the imaginary part ${\ensuremath{\epsilon}}_{2}$ of the dielectric function are considered. The motivation is to study how the symmetry-breaking effects of strain can be used to deduce the symmetry location of the critical points ${\mathrm{k}}_{0}$. This kno…
This report provides a brief preliminary account of the solution crystallization of isotactic polystyrene under the influence of velocity gradients. During crystallizations from 1,3,5-trimethylbenzene and cyclohexanol solutions, the polymer appears in a number of morphological forms which are composed of microfibrilla…
Measurements of the Hall resistivity and magnetoresistance of cadmium and cadmium-zinc crystals in the residual-resistance-ratio range of 40 000-240, corresponding to a maximum zinc concentration of 1.5 at.%, are reported in the temperature ranges of 1.4-4.2, 9-20, and at 77 K for magnetic fields below 25 kG. The Hall…
Reversible phase holograms have been made on thin films of MnBi by Curie-point writing. Magnetic holograms are formed when the interference pattern, created by conventional holographic techniques, heats the film above its Curie temperature, causing a magnetic domain pattern that corresponds to the interference pattern…
Single crystals and polycrystalline 5-mil tungsten wires of high purity were irradiated at 20\ifmmode^\circ\else\textdegree\fi{}K with 2.5-MeV electrons. Stage-I defect behavior was studied by internal friction, dynamic Young's-modulus, and resistivity measurements. The friction and modulus samples were electrostatica…
Studies performed on the conduction and switching phenomena in films of certain amorphous chalcogenide semiconductors indicate that the electrical switching may be associated with a field-influenced dielectric phase transition. The normalized conduction found at voltages below switching displays an Ohmic and an expone…
The thermal conductivity of germanium has been calculated using an anharmonic isotropic continuum model. This model has been extended so as to incorporate umklapp processes by introducing a pseudo-reciprocal-lattice translation vector of magnitude equal to the diameter of the Debye sphere, in such a way that the wave…
The electronic band structure and optical constants of ${\mathrm{Mg}}_{2}$Si, ${\mathrm{Mg}}_{2}$Ge, and ${\mathrm{Mg}}_{2}$Sn are calculated using the empirical pseudopotential method. The results are compared with experiment.
A theory assuming specular scattering of electrons and incorporating nonlocal transverse and longitudinal dielectric functions predicts that a thin metallic film may exhibit anomalous optical properties due to the wave-vector-dependent structure in the longitudinal dielectric function.
Detailed experimental results have been obtained on the reflectivity of both natural and pyrolytic graphite single crystals in the visible and ultraviolet regions. Results have been taken for both $E\ensuremath{\perp}c$ and $E\ensuremath{\parallel}c$ at near-normal incidence, and as a function of angle of incidence fo…
Very unusual and large shifts of the $R$ lines of ${\mathrm{Cr}}^{3+}$ with temperature and applied electric fields were observed. Below the tetragonal transition temperature, these shifts were found to have a behavior similar to that of the reciprocal dielectric constant of SrTi${\mathrm{O}}_{3}$. The electric field…
A detailed account is given of the calculation of the generalized susceptibility functions of Gd, Dy, Er, and Lu using realistic energy bands. These susceptibilities clearly show the influence of the Fermi-surface geometry in determining the helical ordering arrangements of the heavy rare earths, and the ferromagnetic…
A M\"ossbauer-effect study of the low-spin compound ${\mathrm{K}}_{3}$Fe${(\mathrm{CN})}_{6}$ has been carried out under a wide variety of conditions. In concentrated samples, the quadrupole splitting, linewidth, and isomer shift were measured as a function of temperature. The components of the electric-field-gradient…
Sharp-line fluorescence and absorption in the region of 7935 \AA{} were observed in ${\mathrm{Cr}}^{3+}$-doped and undoped SrTi${\mathrm{O}}_{3}$. It is reasonably established that the fluorescence and absorption are due to the $^{2}E\ensuremath{\leftrightarrow}^{4}A_{2}$ transition ($R$ line) of the ${\mathrm{Cr}}^{3…
We optically observe the untwisting and alignment, along an applied magnetic field, of high-pitch cholesteric liquid crystals, mixtures of para-azoxyanisole and cholesteryl esters. The results agree quantitatively with de Gennes's predictions and allow a determination of the twist elastic constant of pure para-azoxyan…
Several cross-linking substances which derive from lysine have been isolated from hydrolyzates of collagen and elastin. This observation suggests that certain lysyl side chains exhibiting enhanced reactivity and unique configuration may participate in cross-linking. In native collagen there is a small family of lysyl…
The effect of molecular interaction between anisotropic (prolate) molecules in liquids on the nonlinear refractive index is studied. The model, without the driving term describing the strong optical-field molecular reorientation, is the same as the Maier and Saupe model of the isotropic to nematic phase transition in…
A Hamiltonian development of the dynamics of the radiation field coupled with an electron gas is presented. The Maxwell equations and the Bloch electron-gas equations are employed in this development. Detailed study is made of first-order coupling between surface plasmons and photons normally incident on a nonuniform,…