INVESTIGATION OF 2-PHASE AND 3-PHASE FIELDS IN THE GA-AS-SB SYSTEM

The technique of annealing samples at a temperature at which both liquid and solid phases occur, followed by quenching to freeze-in the solid phase, has been used to investigate equilibrium conditions off the pseudobinary section. It has been found that large three-phase liquid-solid-solid fields occur corresponding to the two-phase solid-solid field of the pseudobinary section. The tie-lines of the various two-phase liquid-solid fields have been determined together with the boundaries of the three-phase fields at various temperatures in the range 600 degree -730 degree C. The locus of the cusp in the liquidus sheet corresponding to the liquidus point of the three-phase field has also been found. Finally, the two solid phases of the three-phase fields give the ranges of immiscibility in the pseudobinary section GaAs//ySb//1//-//y, and the variation of the miscibility gap with temperature is determined.