The phase diagram of the Ga–S system in the concentration range of 48.0–60.7 mol% S

Our goal is to study the phase T–x diagram of the Ga–S system in the concentration range of 48.0–60.7 mol% S at temperatures up to 1423 K. For this we chose differential thermal analysis (DTA) at low heating rates (< 1 K min−1) as the main research method. In addition to this, we used a new author’s method of chromatic-thermal analysis (CrTA), enabling the experiments to be conducted in a static mode. The obtained DTA data were compared with the results of both CrTA and high-temperature XRD analysis. It was established that, in contrast to the low-temperature part of the diagram, where only Ga2S3 and GaS phases are present, the high-temperature part (1151–1383 K) of this diagram is complicated. It is argued that in a narrow composition range (for the sulfur content from 59.0 to 60.7 mol%) there exist three phases of different compositions; they are denoted as σ, Ga2S3′ and Ga2S3. σ-phase with a sulfur content of about 59.0 mol% S exists in a very narrow temperature range (1151–1195 K) and decomposes at a temperature of about 1195 K according to the peritectic reaction.