Materials Literature
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In an attempt to grow crystals of ammonium acid phthalate with the aim of refining the previously reported gross structure, the diammonium salt was obtained. (NH4)2(OOC. C6H4. COO), orthorhombic, a=6.839 (14), b=13.041 (4), c=22.118 (8)A, Pcab, 0obs = 1.34 Qcalc = 1.34 g cm -3, Z = 8. The structure was solved by direc…
A theoretical model for the calculation of the one- and two-phonon Raman scattering intensities (far from resonance) for covalent crystals is presented. Starting from Placzek's theory, the crystal polarizability is expressed as a sum of individual bond contributions. Instead of the usual "electron-phonon" and "electro…
The homogeneous nucleation of crystals in normal alkane liquids has been studied using a droplet technique for a range of alkanes between C16H34 and C5H12. The critical undercooling for nucleation, ΔTN, relative to the melting point TE, increases significantly with decreasing length of the alkane chain n: ΔTN/TE incre…
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A review of the results of published energy-band calculations for the alkali halides is presented in which the experimental results of the preceding paper are used as a basis for critical comparison of theory and observation. Band calculations employing Slater exchange are shown to be inadequate, while calculations wh…
A unified band-crossing model of the insulator-metal transition in ${\mathrm{Ti}}_{2}$${\mathrm{O}}_{3}$ and the high-temperature tranistion in ${\mathrm{V}}_{2}$${\mathrm{O}}_{3}$ is presented. The model is based on a Hartree-Fock free-energy calculation including electron-electron Coulomb energy, elastic energy, and…
Crystals of BaNaPO 4 were grown from a Ba 3 P 2 O 8 –Na 2 B 4 O 7 melt. The crystals are trigonal, space group [Formula: see text]with a = 5.622(4) and c = 7.259(5) Å. The structure, isotypic with that of glaserite, was refined by full-matrix least-squares methods to a final R value of 0.042 using 218 unique reflectio…
The decay of the excited $^{4}S_{\frac{3}{2}}$ state of ${\mathrm{Er}}^{3+}$ ions in La${\mathrm{F}}_{3}$ at 295\ifmmode^\circ\else\textdegree\fi{}K has been investigated in detail. The energy is transferred from the thermally populated multiplet $^{2}H_{\frac{11}{2}}$. The decay curve of the luminescence from $^{4}S_…
An X-ray integral breadth analysis has been made for the 111, 200, 220, 311 and 222 diffraction profiles recorded on a Geiger counter X-ray diffractometer from the vacuum-evaporated thin films of silver in the range of thickness 580 to 2125 Å. The analysis based on the methods of single and multiple order of reflectio…
Spontaneous magnetostriction of NiO, which consists of two strain components, is reexamined in detail by Berg-Barrett method. The strain components thus determined are e x ' x ' -e y ' y ' =-5.4×10 -4 and e z ' x ' =0.91×10 -4 , respectively. These values are a few times as large as those found previously by Yamada et…
The general spin-relaxation theories of Albers and Deutch and of Argyres and Kelley based on different projection operator methods, and the theory of Freed based on generalized cumulant expansions are compared. It is shown that the first two yield equivalent expressions for the time evolution of the spin density matri…
Measurements are reported of the total charge and its mean position in liquid-charged FEP electrets. A new nondestructive technique has been used. The large difference in decay rates of positive and negative liquid-charged electrets is accompanied by quite different behavior of the deposited charge as it migrates thro…
The interface excitations associated with the inversion layer of a metal-insulator-semiconductor structure are investigated. These excitations can be regarded as coupled modes whose components are the two-dimensional-electron-gas plasmon and the surface plasmon of the metal-insulator interface. The dependence of the c…
The Onsager theory of dissociation has been used to explain the electric field, excitation wavelength, and temperature dependence of photogeneration in amorphous selenium. The Onsager theory was formulated to explain the departure from Ohmic behavior in either weak electrolytes or solid dielectrics, and the analysis o…
An analysis of low-energy-electron-diffraction data from a clean Mo{001} surface was carried out, which has determined the atomic structure of this surface and provided the parameters of a scattering model needed to analyze ordered overlayers. The analysis was based upon the comparison between the intensity spectra ca…
Detailed light and electron microscopical studies on the diatom genus Berkeleya Grev. clarify relationships between the four species and support the separtion of B. fragilis and B. micans as two distinct taxa.
Abstract Die Kristallstruktur von (I) wird durch direkte Methoden bestimmt und anhand von 3‐dimensionalen Röntgenbeugungsdaten verfeinert.
A detailed Raman study of phonons in monoclinic Li 2 SO 4 H 2 O and its deuterate is given. The spectrum for two directions of the phonon wave vector at 45 degrees to the y axis from liquid nitrogen to room temperature have been determined and the majority of the lines observed have been identified: although the conve…
Normal-incidence reflectivity spectra of layer-type beta -GaSe crystals have been measured for E perpendicular to c as well as E//c at 78K. A strong anisotropy in the selection rules for interband transitions has been observed and a suitable energy level scheme is proposed. The reflectivity spectra of the mixed polyty…
Measurements are presented of the temperature variation between 2K and 100K of the thermal conductivity, kappa of several samples of extruded polyethylene. At high temperatures ( approximately 100K) there is an anisotropy in kappa , with the values measured parallel to the extrusion direction up to 5 times greater tha…