Low-temperature synthesis and characterization of Ag₂S_1-xTe_x(0 ≤ x ≤ 1)

Abstract

A low-temperature route for the synthesis of Ag₂S, Ag₂ Te and their solid solutions Ag₂S_{1 -x} Te_x (0 ≤ x ≤ 1) is reported. Ag₂S is prepared by the direct addition of silver nitrate solution to thiourea, while Ag₂ Te is prepared by reacting silver nitrate solution with tellurium in nitric acid and subsequently reducing it with hydrazine hydrate. The solid solutions of Ag₂S and Ag₂Te are obtained by the addition of nitrate solutions of silver and tellurium to thiourea followed by its reduction with hydrazine hydrate. The method enables the synthesis of low-temperature crystalline phase of Ag₂S_{1 -x} Te_x solid solutions. The powder X-ray diffraction studies suggest that the solid solutions of compositions x < 0.3 have a phase akin to α -Ag₂S and those with compositions x > 0.6 are similar to α -Ag₂ Te. In the intermediate range of compositions (x=0.4 and 0.5), the solid solutions are found to be mixtures of α -Ag₂S and α-Ag₂ Te phases which transform totally to α-Ag₂S phase on prolonged annealing at about 473 K.