The phase equilibriums in the FeGa 2 S 4 -FeIn 2 S 4 and FeS-FeIn 2 S 4 systems were experimentally investigated by means of differential thermal and X-ray diffraction analyses. It found that they are quasi-binary and characterized by limited mutual solubility of starting compounds. The phase with composition FeGaInS 4 crystallizes in the FeGa 2 S 4 -type structure, melts at 1375 K without decomposition, and can be characterized as a congruently melting compound by its beh avior in the phase diagram.

The phase equilibria in the MnGa 2 Tе 4 -MnIn 2 Tе 4 system were experimentally investigated by means of differential thermal analysis and powder X-ray diffraction technique. It was found that this system is quasi-binary and characterized by dystectic and eutectic equilibria and the formation of a wide area of solid solutions based on the starting compounds. The crystal structures of the MnGaInTe 4 and MnIn 2 Tе 4 were refined by the Rietveld method using powder X-ray diffraction data. It was established, that both phases crystallize in the tetragonal system (Space group I-42m). Electron paramagnetic resonance and Raman spectra, as well as the temperature dependences of the electrical conductivity and the Hall effect for the MnGaInTe 4 crystal, were studied.

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The crystal structure and thermal properties of AgCuS compound were investigated at high temperature ranges. It was found that the crystal structure of these compounds has orthorhombic symmetry with Cmcm space group at the normal condition and room temperature. The phase transition to cubic symmetry with Fm3m space group is observed at [Formula: see text] temperature. The endoeffect was observed with a central peak at [Formula: see text] in the differential thermal analysis. The temperature dependence on heat capacity was obtained in the range of [Formula: see text] temperature. Thermodynamic parameters have been determined: enthalpy and heat capacity. The value of enthalpy was calculated according to the temperature of the phase transition.

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