Ho2S3-Ga2S3 phase diagram

The Ho2S3-Ga2S3 system has been studied using differential thermal analysis, X-ray diffraction, microstructural analysis, microhardness tests, and density measurements, and its phase diagram has been constructed. The system contains three ternary compounds: Ho3GaS6, HoGaS3, and Ho6Ga10/3S14. Their melting behavior has been studied for the first time. The compound Ho6Ga10/3S14 melts congruently at 1435 K; Ho3GaS6 and HoGaS3 melt incongruently at 1370 and 1250 K, respectively. The Ho2S3-Ga2S3 system is a pseudobinary join of the ternary system Ho-Ga-S. At room temperature, the beta-Ga2S3-based solid solution extends to 1.5 mol % Ho2S3; the Ho2S3 solubility in gamma-Ga2S3 is 10 mol %. The compounds HoGaS3 and Ho3GaS6 crystallize in orthorhombic symmetry (Ho3GaS6: a = 10.40 , b = 13.20 , c = 6.44 , Z = 4; HoGaS3: a = 6.8 , b = 9.92 , a = 3.08 , Z = 4). Ho6Ga10/3S14 has a hexagonal structure (a = 9.62 , c = 6.04 ).