Ferroelectric phase transitions and the Ising model

The Ising model has been an important theoretical tool in the understanding of phase transitions in ferroelectric materials. We first review how it re lates to the underlying physics of order-disorder phase transitions in thes e systems, as well as mean-field results for the spontaneous polarization a nd the dielectric constant near the critical temperature. For hydrogen-bond ed ferroelectrics, a term of interaction with an external transverse field is necessary to account for proton tunneling between the two minima of a. d ouble-well potential. Finally, me discuss both experimental and theoretical results for the problems of proton-lattice interactions, central peak dyna mics, dynamical behavior of pseudo-one-dimensional ferroelectrics and press ure effects on hydrogen bonded ferroelectrics.