Phase equilibria in the Ag4SSe–PbTe system

The phase diagram of the Ag4SSe–PbTe system is built using XRD, DTA and microstructural analysis, as well as density and microhardness measurements. An intermediate compound Ag4SSe·2PbTe exists in it with unit cell parameters of the α-phase: a = 0.3510 nm, b = 0.3053 nm, c = 0.2951 nm, α = 99.07°, β = 94.37°, γ = 89.31°. The compound melts incongruently at 630 °C and goes through a polymorphous transition at Tα↔β = 400 °C. Boundary solid solutions based on the initial compounds Ag4SSe and PbTe, as well as on the new Ag4SSe·2PbTe phase are observed.