On the Growth of ZnS Crystals

概要

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Growth of ZnS crystals was observed in relation to temperature and temperature gradient. When crystals grow in steep temperature gradient zone, growth advances by following three stages : (i) needle crystals grow to the direction of temperature gradient along c-axes. (ii) these crystals assemble themselves into several bundles with their lateral faces adjoining to each other. (iii) a polycrystal with grains which are assembles of the needle crystals grows into a single crystal or a polycrystal with larger grains, releasing grain boundary energy. When temperature gradient is not steep and temperature is high, grain growth progresses faster than the growth by vapor deposition, and grains become large in lateral direction. However, as grains grow in this case with c-axes tending to various directions and the surface tensions of grain boundaries are in balance, a polycrystal with moderate-sized grains grows. Therefore, for obtaining large single crystals it is needed for the crystal to grow in the zone where not only temperature is high enough to advance grain growth but temperature gradient is steep. Comparison with growth by Reinolds method was also described.
東北大学の論文