Materials Literature
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Recent theories of the anisotropy and magnetostriction due to the presence of Co2+ in spinel ferrites are reviewed and new work on the effects of Fe2+ is presented. The effects of these ions are great because the orbital angular momentum is not fully quenched by the crystal field. In the case of Co2+, the orbital mome…
The crystal nucleation behavior of some normal alkane liquids—C16H34, C17H36, C18H38, C24H50, and C32H66—was investigated by the droplet technique. The relative undercoolings, 1—λ, (i.e., the actual undercooling in units of the absolute melting temperature) at which the crystal nucleation frequency in these liquids be…
Abstract It is demonstrated that the various procedures recommended in the literature for the determination of the crystalline fraction in polyethylene specimens by means of X‐ray diffraction lead to consistent results if certain errors made by some of the previous authors are avoided. A simple procedure which is not…
Knight shift measurements have recently been made on a series of compounds having the $\ensuremath{\beta}$-Wolfram structure ${\mathrm{V}}_{3}X$, namely ${\mathrm{V}}_{3}$As, ${\mathrm{V}}_{3}$Au, ${\mathrm{V}}_{3}$Ga, ${\mathrm{V}}_{3}$Ge, ${\mathrm{V}}_{3}$Pt, ${\mathrm{V}}_{3}$Sb, ${\mathrm{V}}_{3}$Si, and ${\mathr…
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Inert marker experiments have shown that the solid‐state reactions forming MgAl 2 O 4 and MgFe 2 O 4 occur by counterdiffusion of the Mg 2+ , Fe 3+ , and A1 3+ ions through the relatively rigid oxygen lattice of the spinel or ferrite. It is suggested that earlier claims that ZnAl 2 O 4 forms by diffusion of Zn 2+ and…
A study of the formation of cubic boron nitride shows that the alkali and alkaline earth metals and their nitrides are effective catalysts for converting hexagonal boron nitride into cubic. The pressure and temperature required varies with the catalyst, and a minimum of about 45 000 atm and 1500°C has been found to be…
Die ONSAGERsche Theorie der „statischen” dielektrischen Polarisation einer Dipolflüssigkeit wird auf die nematische Phase einer kristallinflüssigen Substanz übertragen, wobei die Anisotropie der molekularen Polarisierbarkeit, die Orientierung des permanenten Dipolmoments im Molekül und die nematische Fernordnung berüc…
The principal features of the experimental results of Blewitt et al. (1957) and of Suzuki and Barrett (1958) on deformation twinning in face-centred cubic metals are explained in terms of an extension of the ‘prismatic’ source mechanism of Cottrell and Bilby (1951). Suitable prismatic dislocation sources are thought t…
Results of luminescence studies on chelates of La3+, Sm3+, Eu3+, Gd3+, Tb3+, Dy3+, Tm3+, Yb3+, and Lu3+ are reported. It is shown that the intramolecular energy transfer efficiency is a sensitive function of the relative positions of the resonance energy levels of the ions and the metastable triplet states of the comp…
Abstract Zinc whiskers and platelets with their largest faces in the basal plane and thin enough (~½μ) to be transparent to 100 kV electrons were strained in tension inside the electron microscope and the nucleation and growth of twins observed by the transmission technique. These observations were then related to the…
A calculation of the influence of electron exchange on the dispersion relation of a high-density electron gas at 0\ifmmode^\circ\else\textdegree\fi{}K is described. The result is compared with those obtained by various authors using different methods.
Low-energy electron-diffraction and secondary electron-emission measurements have been made on (111) and ($11\overline{1}$) surfaces of GaSb and (100) surfaces of InSb. To account for the diffraction patterns observed both for these materials and previously for Ge and Si, a general model for (111) surfaces of diamond-…
Abstract The clay mineralogy of a soil profile developed in a New England glacial till has been studied to a depth of 55 in. Degraded soil micas, probably produced by weathering, have been chloritized by both iron and aluminum hydroxide complexes. Aluminum and iron determinations and X-ray analyses indicate that iron…