T-x phase diagram of the In-S system

The T-x phase diagram of the In-S system has been studied by differential thermal analysis and x-ray diffraction between 300 and 1150 degrees C. The compounds identified in this temperature range are InS, In6S7, In3S4, and In2S3. We have determined the temperatures of the monotectic equilibrium L-1(In) + InS = L-2; peritectic equilibria involving InS, In6S7, and In3S4; and polymorphic transformations of InS and In2S3. Our results demonstrate that raising the cooling rate to a certain level leads to a sharp transition from near-equilibrium to metastable phase relations in the In-S system.