Phase equilibria in the GeSe2–PbTe system

The phase diagram of the GeSe2–PbTe system is studied by means of X-ray diffraction, differential thermal analysis and measurements of the microhardness and the density of the material. The unit-cell parameters of the intermediate phase α-GeSe2·(2 − x)PbTe, (x = 0/1) were determined: a = 6.200 Å, b = 3.807 Å, and c = 3.645 Å, α = 106.47°, β = 99.85°, and γ = 87.22°. The intermediate phase α-GeSe2·PbTe receives a peritectic reaction at 425 °C. This phase has variable composition GeSe2·(2 − x)PbTe (x = 0/1), it melts congruently at 425 °C and stands polymorphic transition at Tα↔β = 325 °C, which dependents of the composition (x). The existence of a narrow regions of solid solutions based on PbTe is supposed.