Materials Literature
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A piezospectroscopic study of the Lyman spectra of arsenic, antimony, phosphorus, and magnesium donors in silicon has been made using a quantitative-stress cryostat. Within experimental error, all four impurities yield the same value for the shear-deformation-potential constant ${\ensuremath{\Xi}}_{u}$ of the $〈100〉$…
TE0 mode selection was observed in an asymmetric dielectric light guide with a metal-film outer coating. TM0 mode and higher-order modes could not transmit through the guide, whereas the loss of the TE mode, the insertion loss, was small. The experimental data were in good agreement with the theoretical results given…
A hydrodynamic regime in dynamic scattering has been observed in which the relaxation time depends on the voltage at turnoff. This regime manifests itself, above a threshold voltage, with microscopic regions of increased on-axis optical density which grow until the whole cell area is converted. It has been found in al…
The optical spectrum and exchange splittings of the two types of nearest neighbor Cr3+ pairs in orthorhombic YAlO3 have been studied. The emission spectrum from 7200 to 7350 Å yields the ground state exchange −JS.S+j(S.S)2 with Ja=−24.7, ja=−0.66 cm−1 and Jb=−26.2 and jb=−0.91 cm−1. From the shift of the lines under u…
Potassium in graphite shows distinctive reducing properties towards carbonyls. The reaction products can be related to a mechanism similar to electrochemical reduction. The steric orientation of the reduction can be explained by the particular structure of potassium–graphite.Chromic anhydride in graphite offers a new…
The limiting high frequency permittivity ε ∞ of hexagonal ice, measured using a coaxial three terminal dielectric cell designed to minimize errors arising from differential thermal contraction, varies from 3.093 ± 0.003 at 2 K to 3.15 ± 0.02 at 200 K. The result is discussed in relation to the translational lattice vi…
A general semiclassical derivation is given of the efficiency of the scattering of light from a longitudinal-optical (LO) phonon coupled to a single-component plasma in a semiconductor. The efficiency is the sum of two terms. One is due to the modulation of polarizability by atomic displacements and by the macroscopic…
The compressibilities of the monotellurides of Pr, Sm, Eu, Tm, and Yb and the monoselenide and sulfide of Sm have been investigated to \ensuremath{\sim} 300 kbar using high-pressure $x$-ray-diffraction techniques. SmTe, SmSe, TmTe, and YbTe show abnormal volume changes in the 20-50-, 15-40-, 15-30-, and 150-200-kbar r…
Abstract Transition bands are regions of high lattice distortion which result from inhomogeneous deformation in metals. During annealing of cold-worked metals, nucleation of recrystallization is frequently observed to occur within these bands. An analysis has been made of some of the conditions under which transition…
Widths of photoelectron lines associated with vacancies in core levels immediately below the valence shell are shown to depend on the chemical environment. The width variation is ascribed to change in vacancy lifetime. Valence electron density influences these lifetimes through its effect on Auger transition rates. Co…
The vibrational properties of Si III and Ge III have been studied experimentally using Raman spectroscopy, and theoretically using a simple force-constant model. Si III and Ge III are metastable crystalline phases with large unit cells and distorted tetrahedral bonding.
The crystal structure of meta-nitroaniline, a material which exhibits large nonlinear optical effects, has been determined by single crystal X-ray methods. The arrangement of the molecules found differs from that recently proposed by South gate and Hall (see abstr. A49430 of 1971) on the basis of packing consideration…
Impurity nitrogen in type Ia diamond is known to trap radiation damage centres during annealing. Most of the nitrogen is also known to be present in two forms, labelled A and B from the absorption peaks produced by them in the range 1000-1332 cm -1 . In this paper, the effect of these different forms of nitrogen on th…
A one-electron energy diagram is suggested for magnetite, which is consistent with recent soft-x-ray emission and absorption spectra, cathodoluminescence, and optical-absorption data.Received 22 June 1972DOI:https://doi.org/10.1103/PhysRevLett.29.657©1972 American Physical Society
SUMMARY This paper refers to a case of polymorphism in the desmid Micrasterias laticeps Nordst. It is based on material collected from an artificial pond in the state of São Paulo, Brazil. A detailed examination of almost 400 specimens permitted the authors to give a detailed description of 13 main morphological forms…
The study of the solubility of zinc oxalate is particularly suitable for illustration of the relation between solubility and solubility product because ion pair formation is pronounced and competing side reactions occur.
Abstract On the basis of the diagonalization of the complete ligand field, interelectronic repulsion, spin‐orbit interaction, and Zeeman effect matrices, the magnetic properties have been calculated for the octahedral and tetrahedral d 4 and d 6 electron systems. The calculations were performed according to both the s…
Summary Embreyite is a new mineral that has been found only in old specimens collected at Berezov, Siberia. The composition is Pb 4·97 (CrO 4 ) 2·00 (PO 4 ) 1·91 .0·75H 2 O, or Pb 5 (CrO 4 ) 2 (PO 4 ) 2 . H 2 O based on both wet and electron-probe analyses. Z = I, D meas 6·45, D eale 6·41. Crystals are monoclinic with…
Summary Insizwaite from Waterfall Gorge, Insizwa, is a new mineral with the composition Pt 1·00 Bi 1·35 Sb 0·57 . The name is for the locality and is to be applied to the end member PtBi 2 . The analysed material is an antimonian variety. The mineral is cubic, the unit-cell for the antimonian variety has a 6·625 (2) Å…
Uranium nitride and uranium carbonitride fuel pellets were prepared for irradiation in the Japan Material Testing Reactor. The pellets are 6.9 mm in diameter and 7 mm long, and are of natural and 5% enriched uranium. Uranium nitride powder was prepared from uranium metal via hydride and higher nitride. Uranium carbide…