Growth and characterization of thermal properties of single crystals of solid solutions MnxFe1-xIn2S4

Polycrystals of solid solutions MnxFe1_xIn2S4 were prepared by the two-temperature method. The degrees of phase transformations were defined by differential thermal analysis (DTA), and a phase diagram of the MnIn2S4-FeIn2S4 system was obtained. The phase diagram is described by a narrow crystallization interval and classified as type I according to the Roozeboom classification. Single crystals of solid solutions MnxFe1_ xIn2S4 were grown by vertical gradient freeze method of synthesized polycrystals. The elemental composition of the obtained samples was in good agreement with the calculated composition. The structure was defined by XRD. Prepared samples had a cubic structure, and the parameters of the elementary cell were calculated by the method of least squares. The thermal linear expansion coefficient was investigated in the temperature range T = 80-550 K. Based on the obtained data, the values of the Debye temperature and the root-mean-square atomic shifts were determined, and their concentration dependencies are presented. The thermal conductivity was studied using the absolute method in the temperature range T = 300-550 K. The form of the concentration dependence, the contribution of the lattice and electronic components, and an analytical dependence of the thermal conductivity for the entire range of solid solution were established.