An X-Ray Diffraction Study of Precipitated Cadmium Sulphide

Powders of cadmium sulphide were precipitated with hydrogen sulphide from aqueous solutions of cadmium chloride, bromide, nitrate, and sulphate (and from various mixtures of them) under widely varied concentrations, pH values, and temperatures, and inspected by X-ray diffraction. Hexagonal α-CdS tends to be precipitated from halide solutions, and cubic β-CdS from nitrate and sulphate solutions. Precipitates seem, however, invariably to involve stacking faults of the type proposed in a previous report (R. Sato: Acta Cryst. 15 (1962) 1109). Effects of precipitation conditions on `hexagonality' (fraction of the hexagonal stacking sequence in the crystal) and crystallite-size of products are presented. Attentions are paid to colours of precipitates.