Refinement of the phase diagram of the MnSe–In2Se3 system and the crystal structures of MnIn2Se4 and Mn2In2Se5 compounds

Complex chalcogenides based on transition elements, in particular ternary compounds of the АВ2Х4 type (M = Mn, Fe, Co, Ni; B = Ga, In, Sb, Bi; X = S, Se, Te) are among the important functional materials. Compounds of this class exhibit the phenomena of electronically or optically controlled magnetism and are very promising for the creation of lasers, light modulators, photodetectors, and other functional devices controlled by a magnetic field. Recent studies demonstrated that these compounds can also find application in photocatalysis, photovoltaics, and thermoelectric converters. The study presents new data on phase equilibria in the MnSe–In2Se3 system, obtained by differential thermal analysis, X-ray phase analysis, and scanning electron microscopy. Two ternary compounds, MnIn2Se4 with congruent melting at 1193 K and Mn2In2Se5, melting incongruently at 1196 K, were formed in the system. The first is a phase of variable composition and has a 5–6 mol. % homogeneity region towards an excess of In2Se3. Based on powder diffraction data, the Rietveld method was used to refine the crystal structures and lattice parameters of both ternary compounds