Structure and Thermal Stability of Nanostructured Precursor Powders of Copper(I) Sulfide and Selenide

The hydrochemical precipitation method at 298 and 333 K with, respectively, thiocarbamide and sodium selenosulfate was used to obtain nanostructured powders of copper sulfide with formula composition Cu 2 S, which are composed of globules 200–500 nm in diameter, formed by 70–100-nm particles, and copper(I) selenide, composed of crystallites with polyhedral shape, sizes of 80 to 500 nm, and a formula composition Cu 1.84 Se. An X-ray diffraction analysis revealed the orthorhombic Cu 2 S structure (space group no. 39- Abm2 ) with unit cell parameters a = 1.182 nm, b = 2.705 nm, and c = 1.343 nm. Powders of Cu 1.84 Se copper selenide have a cubic structure (space group Fm3m ) with lattice constant a = 0.5693 nm. A thermal analysis demonstrated that the chemically precipitated Cu 2 S and Cu 1.84 Se powders have a stable elemental composition up to 200–240°C. An intense oxidation of the samples begins at a temperature exceeding 250°C and is accompanied by a sharp decrease in their content of sulfur (selenium) and by an increase in the content of oxygen.