Abstract: | Four intermediate phases are present ; PbGa2S4,orthorombic EuGa2S4-type (a = 20,44 ; b = 20,64 ; ) ; Pb2Ga2S5, orthorombic space group Pbca (a = 12,38 ; b = 11,90 ; ) ; and two Ga2S3-rich solid solutions, one of the wurtzite type at temperatures above 1000°C, one of the distorded blende type below about 970°C. PbGa2S4 has a peritectic decomposition at 930°C, and Pb2Ga2S5 at 900 ± 5°C. The eutectic is at 730°C for about n = 0,80 ( atomic). A glassy region is obtained by quenching the liquid phase and its extent depends on the quenching temperature (at 1000°C, between n = 0,25 and n = 0,50). |