Tracking of dislocations in gel-grown gypsum single crystals

Abstract

Sparingly soluble calcium sulphate dihydrate (gypsum) crystals are grown by the gel method, derived from the diffusion of calcium chloride into the set gel containing ammonium sulphate. By etching (010) matched cleavages (of gypsum grown by above method) with analar grade nitric acid as well as successively etching a thin flake, it has been established that the tracks of dislocations initially make an inclination to the cleavage face and continue almost parallel to the cleavage face, contrary to the earlier findings on natural gypsum [1] where the dislocations are shown to be oblique, parallel lines passing through the body of the crystal. The change in the tracking of dislocations in gel-grown gypsum has been attributed to the role of gel inclusion, as well as a faster growth rate. The implications are discussed.