Phase Relations in the FeSe-FeGa2Se4-FeIn2Se4 System: Refinement of the Crystal Structures of FeIn2Se4 and FeGaInSe4

The phase equilibria in the FeSe-FeGa2Se4-FeIn2Se4 system were studied using the differential thermal analysis (DTA) and x-ray diffraction (XRD) methods. An isothermal section at 700 K, some isopleths sections of the phase diagram, and the projection of the liquidus surface were constructed. The results show that the 2FeSe-FeGaInSe4 section is quasibinary and of eutectic type. The crystal structure of FeGaInSe4 was refined by the Rietveld method, revealing that this compound cannot be regarded as an ordinary substitutional solid solution but as an ordered phase that differs qualitatively from FeIn2Se4 in the occupancy of crystallographic positions.