Triple Well Potential and Macroscopic Properties of Sn2P2S6 Ferroelectrics Near Phase Transition

A possibility of the existence of triple well potential for an order parameter of the second order phase transition in Sn2P2S6 crystals is discussed. The statistical theory was applied for modelling system behaviour in such a case. The model parameters were estimated using available experimental data. The model can explain some peculiarities in temperature dependence of heat capacity.