Differential thermal analysis (DTA) has been performed in order to grow or synthesize the alkaline earth thiogallate compounds that are currently known as useful and attractive phosphors. A big exothermic heat generated at the chemical reaction during synthesis and the pressure hereby produced sometimes prevents the compounds from being synthesized. The DTA measurements give us information to diminish the heat of reaction and hence the pressure due to sulfur. The phase diagrams of the pseudo-binary system for the compounds above have also been constructed from the results of DTA and powder X-ray diffraction. Based on these diagrams, alkaline earth thiogallates and their kindred can be grown form melts. Some compounds are abruptly solidified with supercooling, resulting in fragile polycrystals. Improvement of the shape of a crucible helps a crystalline seed to grow, leading to a single crystal with good quality.