Preparation of uniform colloidal cadmium and lead selenide particles

Colloidal cadmium selenide and lead selenide particles of narrow size distribution were prepared by decomposition of selenourea in solutions of corresponding metal salts. While both salts were crystalline, CdSe powders showed nearly spherical morphology whereas PbSe consisted of particles of cubic symmetry. In the latter case greater uniformity was achieved if homogeneous precipitation was carried out in methanol-water mixtures.