The formation of macroscopic polytypic regions in ZnS crystals

Abstract

Vapor-phase ZnS crystals were grown under strict stabilization of temperature and pressure. Many crystals containing wide polytypic regions were found. Hollow tubes were observed, almost exclusively in the wide regions; the regions with no hollow tubes consist of a large number of very narrow faulted sub-regions. It is suggested that the creation of Shockley partials is associated with the strain in the vicinity of the growth screw dislocations. Those regions where the core of the dislocation is hollow are unstrained and the Shockley partials, moving in from neighboring regions, can climb unimpeded along the helicoidal basal planes, transforming them into the various observed polytypes.