On mechanical and magnetic factors influencing the orientation and perfection of bismuth single-crystals

Abstract

Method of producing crystals of bismuth.—A method is described which permits the production of single crystals of metals, with practically no limit to size or to desired orientation, thus indicating that all external mechanical influences are avoided. Furthermore, the method permits the zone of formation in a growing crystal to be subjected to a strong magnetic field. Mechanical factors influencing the orientation and perfection of crystals.—A systematic study of the conditions in which the seed-crystal transfers its orientation to the rod is made. Experiments with artificially distorted seeds, etc., show that crystalline units must already exist in the liquid state. It is shown that this "liquid crystal" is destroyed at about 10° above the melting point. It is suggested that these units are identical with elementary units of a crystal as treated theoretically by Zwicky and observed by the author. The influence of a magnetic field on a forming crystal.—Crystals in the three main orientations to the directions of the field lines (20,000 Gauss) were grown, one-half with, the other half without field. No change in the orientation between both halves could be observed as long as no secondary influence was present. However, crystals grown without a predetermined orientation indicated a preference for an orientation in which the direction of the smallest diamagnetic susceptibility (along the trigonal axis) was parallel to the lines of force. The fact that this influence, though much smaller than the orienting forces of a seed, exists, supports the assumption of "block-phase" slightly above the melting point.

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