POLYMORPHISM OF GA2S3 AND PHASE-DIAGRAM OF GA-S

The monoclinic form ( alpha prime ) of Ga//2 S//3 is exactly stoichiometric and is stable from room temperature to the melting point. The hexagonal form ( alpha ) and the wurtzite-type form ( beta ) exist only at high temperature, above 885 degree C; their formation requires a very small sulfur deficiency and, consequently, they are obtained in the presence of GaS. The passage from the hexagonal form to the wurtzite form is progressive and depends on the proportion of GaS. The blende-type form is clearly substoichiometric (GaS//1//. //3//8) and exists only in a small temperature range. The phase diagram is described from GaS//0//. //9//6 to GaS//1//. //5//6.