The influence of cation impurities on phase transitions in the TlInS2 compound

The temperature dependences of the permittivity of TlInS₂ crystals doped with 0.1 at. % Cr, Mn, Yb, Sm, Bi, or La are investigated, and the dependence of the phase transition temperature on the ion radius of the dopant impurity is determined. It is revealed that manganese and chromium substitute for indium in the TlInS₂ crystal lattice, whereas ytterbium, samarium, bismuth, and lanthanum ions occupy octahedral holes in an In₄S₁₀ tetrahedral complex and, thus, produce an internal pressure responsible for the shift in the temperature of phase transitions toward the high-temperature range.