Pseudobinary phase diagram and existence regions for PbS1?xSex

The pseudobinary phase diagram of the PbS_1−xSe_x system has been re-determined by using thermal analysis to measure the liquidus temperatures and electron microprobe analysis of the first-to-freeze portions of Bridgman-grown ingots to establish the solidus points. The minimum in the liquidus occurs at x = 0.73 and 1076° C. The separation between our solidus and liquidus curves is considerably less than Simpson reports. For PbS_1=xSe_x alloys with 0. 35 ≼ x≼ 0.41, the existence region between 300 and 800° C has been determined by means of Hall coefficient measurements at 77K on Bridgman-grown crystals that were either Pb-saturated or chalcogen-saturated by isothermal annealing and then quenched. Both the Pb-rich and chalcogen-rich solidus lines are retrograde, and the existence region is nearly symmetrical about the stoichiometric composition. New data for the retrograde S-rich solidus of PbS have also been obtained. This work was sponsored by the Department of the Air Force.