Impurity- and temperature-dependent structural transformations in polytypic crystals of CdI2, PbI2 and CdBr2

Single crystals of polytypic materials CdI2, PbI2 and CdBr2 were purified and grown at high temperatures by use of zone-refinement and Bridgman-Stockbarger techniques. The crystals were investigated by X-ray diffraction to ascertain how the purification of crystals influences the growth and polytypism of crystals. The results obtained were compared and correlated with various other studies made on crystals of these materials with special reference to the effect of purification, presence of impurities and the temperature. (orig.)