Investigation of the Pr2Se3–Cu2Se–PbSe and Pr2Se3–Ag2Se–PbSe systems

Phase diagram of the Cu2Se–PbSe system was constructed using differential-thermal analysis, X-ray diffraction and metallography. The eutectic reaction L ⇔ β-Cu2Se + PbSe takes place at 886 K and corresponds to 46 mol% PbSe. The peritectoid reaction β-Cu2Se + PbSe ⇔ α-Cu2Se takes place at 420 K. The formation of the PrCuSe2 compound (LaCuS2 structure type, space group P21/c) and the solid solution range Pr2Se3–Pr2PbSe4 (Th3P4 structure type, space group I4¯3d, a = 0.89916(2) nm, RI = 0.0682 for Pr2PbSe4) was confirmed using X-ray powder diffraction. The interactions between the components in the Pr2Se3–Cu2Se–PbSe and Pr2Se3–Ag2Se–PbSe systems at 870 K were determined using X-ray powder diffraction. No quaternary compounds exist in these systems.