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

Compounds in the IIa–III2–VI4 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–In2S3 and the BaS–Ga2S3 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–Ga2S3 systems was also found in both diagrams. The melting point of BaIn2S4 is determined as 1062 °C, while that of BaGa2S4 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., BaIn2S4, BaGa2S4, and BaGa4S7, a single crystal of BaIn2S4 has been successfully grown by the melt method using a specially devised carbon crucible for escaping from the big supercooling always observed at solidifying.