Non-equilibrium Thermodynamic Theory of Ferroelectric Phase Transitions

In this review, the non-equilibrium (or irreversible) thermodynamic theory of ferroelectric phase transitions was expounded systematically. Firstly, the limitations of the classical thermodynamic theory of ferroelectric phase transitions (known as the Landau-Devonshire theory) were reviewed critically. The unpleasant consequence caused by the metastable states hypothesis, and the evidence for the non-existence of metastable states i.e. the logical conflict, and the evidence for the existence of stationary states were shown. Secondly, the non-equilibrium thermodynamic description of (especially the first-order) ferroelectric phase transitions was given. The evolving, local characteristics of ferroelectric phase transitions were described well by using the principle of minimum entropy production and the generalized Onsager reciprocal relations. The thermo-electric coupling case is a reduced one of the thermo-electro-mechanical coupling case. In the realm of non-equilibrium thermodynamics, the relation between the latent heat and the polarization was given, too. Thirdly, the non-equilibrium thermodynamic explanation of the irreversibility of ferroelectric phase transitions, i.e. the thermal hysteresis and the domain occurrences in ferroelectrics, was given. At last, some concluding remarks were made and we looked forward to some possible developments.