Phase diagrams of the pseudo-binary systems of BaS–In2S3 and BaS–Ga2S3

Abstract Compounds in the IIa–III 2 –VI 4 system are expected as luminescent materials when doped with RE elements, and especially their single crystals are regarded as promising for variable-wavelength lasers in the visible region. However, except for (Ca, Sr) thiogallates, few reports concerning the single crystal growth have been published so far. Here, the pseudo-binary phase diagrams of the BaS–In 2 S 3 and the BaS–Ga 2 S 3 systems have been constructed for the first time, and based on them the single crystal growth of the compounds above has been performed. A eutectic reaction similar to that in the (Ca,Sr)S–Ga 2 S 3 systems was also found in both diagrams. The melting point of BaIn 2 S 4 is determined as 1062 °C, while that of BaGa 2 S 4 is too high (predicted as more than 1250 °C) to be measured in our apparatus. Among three possible compounds found in this study, i.e., BaIn 2 S 4 , BaGa 2 S 4 , and BaGa 4 S 7 , a single crystal of BaIn 2 S 4 has been successfully grown by the melt method using a specially devised carbon crucible for escaping from the big supercooling always observed at solidifying.