Preparation and stabilization of γ-La2S3 at low temperature

Eu doped gamma-La2S3 were synthesized by the sulfurization of their oxide powders using CS2 gas at 700 degrees C. During the sulfurizing reaction process, the cubic Eu3S4 crystals of prior formation acted as the nuclei sites of the gamma-La2S3 phase to facilitate the nucleation process. The gamma-La2S3 transformation occurred at significantly lower temperature by the combined contributions of low transformation enthalpy and induced multiple nuclei. On the other hand, the doped Eu ions could be inserted into the empty tetrahedral S-4 cavities to stabilize the gamma-La2S3 phase at temperature excess of 1100 degrees C.