Materials Literature
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A theoretical estimate of the polarizabilities of ions in the alkali halides is made by means of a procedure based upon the product approximation which distinguishes the ionic constituents in the crystals but allows for their overlap and mutual interaction. Analysis by means of the Thomas-Kuhn sum rule is used allowin…
Below 1.2\ifmmode^\circ\else\textdegree\fi{}K, the specific heat of natural Madagascar graphite is: $C=13.8T+27.7{T}^{3}$ \ensuremath{\mu}J/mole deg. The coefficient of the linear term agrees well with theoretical calculations of the electronic specific heat of a pure single crystal of graphite. The ${T}^{3}$ term yie…
This paper describes an experimental and theoretical examination of a 10-\ensuremath{\mu}g $c$-axis-oriented single crystal of MnAs. The critical magnetic field for the first-order transition to the ferromagnetic phase has been measured as a function of temperature (15 to 65\ifmmode^\circ\else\textdegree\fi{}C) and pr…
The crystal structures of the isomorphous garnet-red copper salts, KCuCl3 and NH4CuCl3, have been determined. Each compound contains discrete, planar, Cu2Cl6= dimers. These dimers are stacked above each other along the crystallographic a axis. The cation exhibits a ninefold coordination. KCuCl3 is antiferromagnetic be…
An apparatus for tensile testing in vacuum to 5400°F is described. A load-elongation curve is plotted during testing of a standard specimen at a selected nominal strain rate between 0.005 and 5.0 in./in./min. The load train design provides that the grips, as well as the specimen, are in the furnace hot zone. The speci…
The methods commonly used in making buckling, critical loading, and cell parameter measuremerts are reviewed, and the results of such measurements are summarized. Only simple uniform and multiregion lattice experiments are considered. The experimental work done at each of the laboratories involved is summarized. The m…
Visual observation of the freezing and melting of compounds in cells used for the determination of purity has uncovered some heretofore unexpected behavior. This behavior has been correlated with certain difficulties experienced in the measurement of purity, particularly when the sample is very pure. Means for partial…
Abstract 1. It is determined by study of the accumulation of peroxides in atactic polypropylene that ozone acts as an initiator of oxidation and considerably accelerates the course of the reaction even at room temperature. 2. The surface of the oxidized specimens is an important kinetic factor in the accumulation of t…
Calculations of the energy and angular dependence of the polarization of 1 to 2 keV electrons elastically scattered from mercury agree qualitatively with experiment, a maximum 90° polarization occurring at 1.5 keV as found experimentally.
Abstract Stretched films from partly unsaturated natural rubber hydrochloride develop cracks and fracture in ozonized oxygen. Cracking occurs only above a minimum stress level of about 70 kg./cm. 2 . Ozone sensitivity increases exponentially with stress, but goes through a maximum near the yield point of the thermopla…
Abstract The dynamic shear modulus at very high strains, ( G ∞ ), of carbon black filler loaded vulcanizates is regarded as due to the product of two factors : ( a ) a hydrodynamic interaction due to filler particles, and ( b ) a second factor for which evidence is given suggesting that it arises from a few strong lin…
The heat content of uranium dicarbide was measured from 1484° to 2581°K using a drop calorimeter.
Abstract The degradation of a polycarbonate by electron irradiation in oxygen and in vacuum has been examined. It was found that the polymer undergoes chain scission and that crosslinking apparently did not occur, the molecular weights of irradiated specimens were therefore determined from the intrinsic viscosity of m…
The optical constants of liquid tellurium at 500 and 600°C have been measured by a reflection method in the spectral range 4000 to 23 000 cm−1 (2•5 to 0•43 microns). The conductivity σ(k) for wave number k is considered as the sum of two terms, σc(k) due to intra-band transitions and σv(k) due to inter-band transition…
Abstract Bei der thermogravimetrischen Zersetzung von Praseodymchromat(VI) geben die Abbaukurven keine Hinweise für die intermediäre Bildung von Praseodymchromat(V). Trotzdem konnte durch analytische und röntgenographische Untersuchung partiell abgebauter Pr 2 (CrO 4 ) 3 ‐Präparate die Existenz des thermisch sehr inst…
In order to obtain some information about the effective electron number of nitrogen in ${\mathrm{Mn}}_{4}$N, the x-ray atomic scattering factors of nitrogen and manganese were measured by Fe $K\ensuremath{\alpha}$ radiation. The experimental values of the scattering factor of nitrogen determined within a resultant pro…
Abstract The kinetics of polymerization of butadiene and isoprene with butyllithium initiator have been studied both in n ‐hexane and tetrahydrofuran solution. The overall polymerization rates were much faster in the THF solutions than in n ‐hexane, and the latter also exhibited relatively slow initiation rates compar…
Abstract Column leaching experiments with 0.001 N CsCl with 1 N KCl or CaCl 2 showed Cs sorption by a number of clays to be much larger from Ca than from K solutions. The sorption affinity of Cs relative to the complementary ion corresponded with that found by others for the Cs‐K ion pair, but in Cs‐Ca systems the Cs…
The growth of germanium dendrites containing two twin planes has been investigated. The solution of the heat flow problem in the stem of a growing dendrite being pulled from a melt permitted the design of experiments suitable for testing theory. The limiting growth velocity was determined as a function of melt underco…
A technique is described for testing rutile single crystals in compression at elevated temperatures. The stress‐strain behavior of crystals of four different orientations was examined up to temperatures in excess of 1000°C, and a dependence of both the flow stress and the rate of work hardening on crystal orientation…