Solid solutions in the Ag2Se-PbSe-Bi2Se3 system

Abstract

The phase equilibria in the pseudoternary system Ag2Se-PbSe-Bi2Se3 have been studied using differential thermal analysis, x-ray diffraction, and microhardness measurements. The results have been used to construct the T-x phase diagram along the AgBiSe2-PbSe join and the 900-K section of the ternary phase diagram. The AgBiSe2-PbSe system contains a continuous series of cubic solid solutions with the NaCl structure. Their lattice parameter is an almost linear function of composition (a = 5.822–6.125 A). The formation of the solid solutions stabilizes the high-temperature phase of AgBiSe2: PbSe dissolution in this compound markedly reduces its polymorphic transformation temperature (590 K), down to room temperature at ≃ 10 mol % PbSe. In the Ag2Se-PbSe-Bi2Se3 system, the γ-phase exists in a broad region around the AgBiSe2-PbSe pseudobinary join.