Thermal properties of TlCdF3 and RbCaF3 near their phase transitions

The specific heat of single crystals of TlCdF3 and RbCaF3 which belong to the perovskite family and undergo a ferroelastic transition at 187.2 K for TlCdF3 and 198.2 K for RbCaF3, is measured between 150 and 240 K. The analysis of the data shows that critical exponents α = 0.66 and α′ = −0.33 account for the strong anomaly of the specific heat, respectively above and below the transition.