Materials Literature
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A simple method is proposed for calculating by hand the thickness of surface films using data obtained from the microprobe analyser. It is shown that, if one exploits the scaling properties of electron scattering distributions, a set of curves may be obtained representing the fraction of characteristic ionization prod…
A critical examination is presented of the available experimental evidence relating to the frequency dependence of the electrical conductivity of a wide range of disordered and amorphous semiconductors and insulators. It is pointed out that there is no justification for regarding these effects as true bulk phenomena,…
An experimental study of critical phenomena in thin ferroelectric films is presented which, for the first time, conclusively demonstrates that the polarization in thin films is drastically reduced as a result of depolarization effects. Other causes, like impurities, structural defects, and domain formation, which can…
The existence of a monoclinic phase of hydroxyapatite, Ca(2)(PO(4))(4)OH, has been confirmed, by single-crystal structure analysis (weighted "reliability" factor = 3.9 percent on |F|(2)). The structure has space group P21/b, a = 9.4214(8) angstroms, b = 2a, c = 6.8814(7) angstroms, and gamma = 120 degrees , and is ana…
The formation of the polyoctamolybdate ion [Mo 8 O 6- ]n results from two condensation principles. First the octamolybdate ion [H 2 Mo 8 O 28 ] 27 6- is formed by stepwise aggregation according to the condensation mechanism formerly proposed 2 . This species is subjected to a polycondensation resulting in an octamolyb…
Summary In this work, the effect of the corrosion accelerating substances sulphur dioxide and nitrate, which may be present in foods as residues was investigated. The amount of dissolved tin and iron were taken as the corrosion criteria. Sulphur dioxide was found to act as a corrosion accelerator, in an acid medium of…
Abstract Infrared frequency band assignments are given for Group IV A polyesters and polyoxides of the below form: magnified image The infrared band assignments are in general agreement with those reported for the corresponding mono‐ and diesters and oxides. Either or both (d‐p)π bonding or sigma electronic inductive…
Abstract A previously suggested new theoretical model for the extension of the charge density of 3d electrons of atoms of ferromagnetic metals of the iron group (in comparison to that in a free atom) and a concept of a neutral atom in metals is considered and on the same basis a calculation has been made for the elect…
The necessity and difficulty of developing an ideal formulation of a chemical coating for optimum man-made fiber processing on textile equipment under varying conditions is stressed. In the absence of such a coating, the fiber has little economic value. The phrase "spin-finish" is defined. The various compounds chiefl…
Summary Phosphate minerals of the plumbogummite group were tentatively identified in a strongly weathered and leached New Zealand soil formed from granite by comparing changes in inorganic phosphate fractions, after calcination, of a soil sample with those occurring in Christmas Island rock phosphate. This identificat…
Relaxation processes were studied in bulk B 2 O 3 glasses compacted under hydrostatic pressures up to 21 kbars at room temperature. Measurements of room‐temperature density and refractive index at 1 atm revealed that (1) more than one ordering parameter is required to describe observed time‐dependent volumetric behavi…
Many crystalline host lattices are known which form porous crystals stabilized by the presence of entrained guest species but which sometimes (e.g., zeolites) exist as porous structures in the absence of guest molecules. Porous crystals form a large physically and chemically diverse group frequently augmented by new d…
We have determined the energies and linewidths of excitons and of one- and two-magnon states in the antiferromagnetic perovskite RbCo${\mathrm{F}}_{3}$, by laser-light scattering experiments. Because ${\mathrm{Co}}^{2+}$ ions at octahedral sites have orbital angular momenta which are unquenched by the crystal field, t…
A formal description of angular correlations in fluids is presented. The method of functional Taylor expansion is used to formulate expressions for correlation functions. An approximate potential for rodlike particles, a generalized Ornstein-Zernike equation, and a generalized Percus-Yevick equation are used in the ca…
Summary A kinetic and X-ray study of the dehydroxylation of datolite, CaBSiO 4 (OH), has shown that the decomposition occurs very rapidly above 700°C in air, with an activation energy for the reaction of the order of 200 kcal mole −1 . The transformation is topotactic, the dehydroxylated phase being tetragonal with a…
The pressure dependence of the specific heat of high-density polyethylene was determined from simultaneous measurements of thermal conductivity and diffusivity in a cylindrical geometry at 300 K and in the pressure range 0–25 kbar. The thermal conductivity and the diffusivity both increase strongly with pressure, the…
Abstract Molar volumes of substantially amorphous polymers may be calculated by using additive constants derived from constitutive atomic and structural parachor contributions. For 34 polymers, ranging in density from 0.83 to 2.03 g/cm 3 , the greatest error in the calculated molar volume compared with the measured va…
Abstract The far ultraviolet absorptions of aliphatic amino acids such as glycine, alanine, aminobutyric acid, valine, and leucine were measured with their solid thin films down to 120 nm. Four absorption bands arising from the carboxyl group were observed in the 200–140 nm region. It was found that the band positions…
Abstract The efficiency of production of F centres in CaF 2 by X‐irradiation has been studied as a function of temperature and compared with the results of an earlier detailed investigation of SrF 2 [1]. The efficiency begins to fall gradually at about 20 K and at 100 K has reached a very low value. It does not recove…
Polycarbonate is a polymer which exhibits extreme toughness, a pronounced yield behavior, and the ability to flow extensively prior to fracture. These characteristics coupled with its birefringent properties indicate its suitability as a model material for photoelastic analyses. This study treats the photoplastic resp…