GB875774A - A process for making cupric, mercuric and plumbous selenides - Google Patents

Abstract

Cupric, mercuric or plumbous selenides are prepared by treating the selenites of the respective metals with hydrazine hydrate at a temperature of at least 50 DEG C. A selenite of copper, mercury or lead of high purity is added slowly to 85% hydrazine hydrate, diluted with water if necessary to avoid too vigorous a reaction, in molar proportion of selenite:hydrazine hydrate of 1:4 to 1:14, especially 1:7, at 50 to 120 DEG C. preferably 75-100 DEG C. For the production of cupric or plumbous selenide, preferable temperatures are 80-85 DEG C. The reaction, which is exothermic and once started requires no external heating, is allowed to continue until the evolution of nitrogen ceases, e.g. after 1/4 -5 hours, the resultant solid product being isolated by filtration, washed free of mother liquor and dried. The reaction is preferably catalysed by the presence of an anion of a lower aliphatic carboxylic acid, introduced into the reaction mixture as the free acid or as a metal salt, the metal ion of which corresponds with the metal ion of the selenite employed. Catalysts referred to are formic, acetic, propionic, butyric or benzoic acids, mercuric acetate, lead acetate, or lead benzoate. For use as semi conductor materials the selenides thus prepared may contain "activators" of Cu or Ag, in quantities of 0.01% mole or less, added in the form of a copper or silver selenite to the copper, mercury or lead selenites before the reaction with hydrazine hydrate.