Materials Literature
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The effect of impurities is inexplicable by the accepted theory of crystal growth. In this report a mechanism is presented which describes the specific action of crystal-growth poisons. By this model the step motion in growth is hindered and nucleation rate on an ideal surface is increased. To rationalize the effect o…
On the faces of a type I diamond octahedron of particularly good quality there have been observed clusters of trigons which appear to be associated with a centre of strain in the interior of the stone. The trigon patterns show features which can only have been the result of surface dissolution. These observations are…
The structure of the conduction band of Ge is completely taken into account in calculating the cross section in second-order Born approximation. The second-order matrix element contains first-order matrix elements of electron-photon interaction (derived for anisotropic mass) and of electron-scatterer interaction. Scat…
The magnetic-field-dependent data of Soule for the Hall effect and magnetoresistance in graphite have been analyzed using a multicarrier model. An improved mode of analysis is used, in which the magnetoconductivity tensor elements are computed as functions of magnetic field strength from experimental data, and then fi…
Abstract Measurements of crosslinking, trans ‐vinylene formation, and hydrogen evolution have been made on high‐ and low‐density polyethylenes irradiated at temperatures from about −170 to +240°C. Crosslinking produced during irradiation is mainly in the amorphous areas of the polymer; whereas trans ‐vinylene unsatura…
The bands of the γ system of the PO molecule have been photographed under high dispersion (0.35 Å/mm). A rotational analysis of the 0–0, 0–1, and 1–0 bands is given, which differs from the one previously given by Sen Gupta. In addition, four more bands, namely, the 1–2, 2–1, 2–3, and 2–4 bands, have been analyzed. The…
Ranges of solid solution have been investigated in systems composed of either two A 2 III B 3 VI compounds or one A III B V and one A 2 III B 3 VI compound. It is found that in practically all cases considered complete solid solution throughout the whole range of composition can be obtained, but that in some cases thi…
Measurements of the electrical conductivity, Hall coefficient, thermoelectric power and Nernst coefficient on specimens cut from zone melted Bi 2 Te 3 and on a single crystal are described. The current flow was parallel to the cleavage planes and the galvanomagnetic effects of the single crystal were measured with the…
A general review of luminescent materials is given, with some emphasis on the more recent applications. The theoretical aspects of the absorption and emission processes are discussed briefly.
Abstract Although the production of foam rubber on an industrial scale has been for a considerable time a rather well-controlled process, all factors involved are still insufficiently known. The most critical phase of the manufacturing process is undoubtedly the gelation of the foam produced. This consists of a clotti…
Abstract The rational synthesis of the ‘cyclic’ tetranuclear p ‐cresol novolak ( VIII ) from the corresponding resole ( VII ) which was synthesized from 3‐bromo‐2:2′‐dihydroxy‐5:5′‐dimethyldiphenylmethane ( I ) has been accomplished in accordance with the scheme given below. A molecular model of the resole ( VII ) ind…
The yield and fracture stresses of unirradiated and irradiated End steel have been measured at 20°, −78°, and −196°c. From the change in yield stress, [sgrave], (shear), with grain size, 2d, the values of [sgrave] i and kv in a Petch type equation, [sgrave]v=[sgrave] i +kv d −1/2, have been determined. The term kv is…
Magnetic properties of synthesized solid solutions of ilmenite (MgTiO 3 , MnTiO 3 , FeTiO 3 , CoTiO 3 and NiTiO 3 ) and hematite (αFe 2 O 3 ) are investigated and it was confirmed that those of any ilmenite-hematite series can be divided into three parts: i) pure ilmenite, ii) solid solutions with R\bar3 crystal symme…
Abstract The bands due to stretching of OH groups in celluloses I, II and III I have been studied with plane polarized infrared radiation. The spectra show that all three crystalline modifications contain OH groups which make an angle much smaller than 55° with the chain direction, while other OH groups make angles gr…
New techniques are described which permit one to reverse the direction of the spontaneous polarization in liquid-electroded single crystals of BaTi${\mathrm{O}}_{3}$ with one growing domain which nucleates at a predetermined location on the crystal and then expands through sidewise 180\ifmmode^\circ\else\textdegree\fi…
Abstract The cracking of rubber by atmospheric ozone is now a well-known phenomenon and for a number of years rubber scientists and technologists have devoted considerable effort to combating it. While the differences of opinion and the confusion of data in this work are sometimes more conspicuous than the successes,…
Abstract The freezing point depression of polymer solutions was measured in the concentration range 5% to 30% (by volume of polymer), particular attention being paid to avoid excess supercooling. The polymer‐solvent combinations investigated were polystyrene‐benzene, polyvinyl acetate‐benzene, cellulose acetate‐acetic…
The technique of multiple factor analysis has been used to study the factors that affect the ‘handle’ of suiting materials. Unskilled observers describe the feel of these fabrics mostly in terms of smoothness, softness, coarseness, thickness, weight, warmth and stiffness. The relationship between these qualities and o…
An explanation based on kinetic considerations is developed for the failure of some pure liquids to crystallize. The important parameters are (1) α, the ratio of the molar liquid-solid surface tension to the heat of fusion ΔHf, (2) β, the ratio of the entropy of fusion to R, (3) ΔG′, the kinetic barrier to nucleation,…
The magnetic structure of ${\mathrm{Fe}}_{4}$N has been examined in a neutron diffraction study. The results are in agreement with a model proposed by Wiener and Berger on the basis of magnetic measurements on a series of related compounds. Ferromagnetically aligned moments of 3 ${\mathrm{\ensuremath{\mu}}}_{\mathit{B…