Thermodynamic and transport properties of K3TbX6 congruently melting compounds formed in TbX3-KX binary systems (X = Cl, Br)

Thermodynamic (temperatures and enthalpies of phase transitions, heat capacity) and transport (electrical conductivity of solid phase) properties of K3TbX6 compounds are well correlated with their crystal structure. Specific dependence of heat capacity and electrical conductivity of solid phase of K3TbX6 compounds can be explained as a result of disordering of cationic sublattice formed by potassium cations. The state of ‘complete disorder’ of cationic sublattice is obtained in high temperature modification. In this state potassium cations are randomly distributed between TbX6 octahedra, which form anionic sublattice.