Materials Literature
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The low-temperature thermal conductivity $K$ of undoped $n$-type InAs has been measured between 5 and 300 \ifmmode^\circ\else\textdegree\fi{}K, and analyzed on the basis of three different approaches, each including boundary-effect, mass-difference-scattering, and phonon-phonon processes. Various required parameters,…
Mg_6Pd represents the second of the two structure types so far found for complex A_6B compounds of cubic symmetry containing about 400 atoms each per smallest unit cube, arranged according to space group F4{bar]3m. The first type is represented by Na_6Tl. A complete structure determination has been carried out for Mg_…
It is shown that many-body interactions can play a dominant role in nonradiative energy transfer processes between ions in crystals. These interactions formally arise from the Coulomb and exchange interactions between the electrons of the donor ion and two or more acceptor ions. In particular, three-body transfer proc…
CO adsorption on Cu(100) has been found to be completely reversible over the temperature range 77–300°K and pco=10−8−10−4 torr using LEED and work function measurements. The isosteric heat has been determined as a function of coverage, and strong correlations have been found with surface structural changes. An in-regi…
Calculations are presented in connection with a theoretical interpretation of noncubic components in the optical emission spectra of CaF 2 :Dy 3+ system. It is shown that the symmetry of the noncubic centres in the system is tetragonal (C 4v ). Crystal field parameters arrived at are (in cm -1 ): B (2) 0 =298, B (4) 0…
Abstract Polyimides were synthesised from a number of diamines and dianhydrides and their stability determined by thermogravimetric analysis at 400°C in air. Wherever possible high molecular weight films obtained by thermal condensation of the polyamic acid intermediates were studied. If this was not possible, films o…
CeD 2.0 , CeD 2.15 and CeD 2.75 have been examined by neutron diffraction. CeD 2.0 has the ideal fluorite structure. In both CeD 2.15 and CeD 2.75 , interstitial deuterium atoms are displaced about 0.2AA from the position 1/2, 1/2, 1/2 position and there is evidence of a small concentration of normal deuterium vacanci…
In cubic solids the elastic properties cannot affect the sign of the thermal expansion, but in axial solids negative thermal expansion can arise not only from anisotropy in the Gruneisen functions, but also from elastic anisotropy. The origin of negative thermal linear expansion is discussed for arsenic, graphite, sel…
A twin in a crystal can terminate at a partial wedge disclination. This is the analogue to a stacking fault terminating at a partial dislocation. It is illustrated for an FCC crystal. Similarly, several twins can terminate at a partial disclination. This is also illustrated for an FCC crystal. Crystals with such defec…
Abstract Tail tendons from Fischer and Sprague-Dawly albino rats of ages from 2 weeks to 3 years were investigated under the polarizing microscope as regards structure and deformation behaviour. Periodically extinguishing bands were observed along the otherwise featureless tendons. By analysing the behaviour of this e…
Abstract A description is given of measurements made of the viscoelastic properties of six organic liquids in the supercooled state. A new experimental system has been used, which was designed to give results at 30 MHz of an order of magnitude greater accuracy than previous techniques. The measured values of the shear…
The temperature dependence of the elastic constant $\frac{1}{2}({c}_{11}\ensuremath{-}{c}_{12})$ shows that the ${B}_{1g}$ acoustic phonon branch is the soft mode at the cooperative Jahn-Teller phase transition in DyV${\mathrm{O}}_{4}$. For $T>2{T}_{ D}$ (${T}_{ D}$ is the transition temperature) the data can be de…
A form for the relaxation shape function for a Heisenberg paramagnet is proposed which has the merit of satisfying certain sum rules and limits. It is shown by comparison with exact infinite-temperature calculations by Carboni and Richards, and inelastic neutron scattering measurements by Hutchings et al. on ${(\mathr…
On décrit un dispositif qui mesure de façon absolue le facteur de réflexion de surfaces optiques, et ce dans un domaine spectral s'étendant de 0,3 à 12 μm. Sa géométrie lui permet en outre de mesurer le coefficient d'absorption de couches minces sans support.
We present a quantum mechanical treatment of thermal transport in a one-dimensional isotopically substituted harmonic lattice. This work is an extension of a classical mechanical treatment. We find that the difference between the quantum and classical expressions for the thermal conductivity of a random chain vanishes…
Three length groups of cotton (1.04, 1.09, and 1.15 in. 2.5% span length), each comprising 8 two-bale mixes, were spun on a Tru-Set (Saco-Lowell Duo-Roth) drafting system at four different cradle openings centered about the cradle opening that gave minimum end breakage for 40s carded yarn. Drafting force measurements…
An apparatus and method is described for the growth of large, flawless, high-purity, oriented, single crystal cylinders (at least 50 mm in diameter by 55 mm long) of cerous magnesium nitrate 24 hydrate [Ce2Mg3(NO3)12·24H2O; (CMN)]. The CMN single crystals are grown at 30 °C in an air thermostat by evaporation of a sat…
Abstract The electrical conductivity over the range of 300 to 1300 °C and the thermoelectric force (700 to 1300 °C) have been measured on monocrystalline samples of cobalt aluminate. Calculations were made for the drift mobility; the values of the mobility are shown to be low (10 −2 to 10 −4 cm 2 /Vs). The drift mobil…
An anomalous rate minimum exists at about 400 °C for the oxidation of plutonium, i.e., there is a decrease in the oxidation rate as the temperature is increased toward the rate minimum. In situ X-ray diffraction studies have shown that in the temperature region of the rate minimum, there is an increased rate in the fo…
Abstract Tail regeneration occurs following autotomy of the tail in the salamander Desmognathus fuscus. Studies based on histology and autoradiography suggest that the cells of the regeneration blastema arise from the connective tissue of the tail stump. Following autotomy of the tail in Desmognathus the muscle of the…