Phenomenological theories of ferroelectric phase transitions

Abstract Phenomenological theories for ferroelectrics are based on Landau–Devonshire type models, which can be constructed based on thermodynamic principles and symmetry relationships between parent and product phases. Phenomenological theories can be directly linked to measurable macroscopic quantities and at the same time preserve microscopic information. The competition between gradient energy and non-linear energy in Ginzburg–Landau type models provides an interpretation of inhomogeneous structures in ferroelectrics, for example twins and domain walls. Phenomenological models can be extended to antiferroelectric systems using a multicomponent order parameter related to microscopic local dipoles, rather than the average polarisation vector. Such a model can provide a more rigorous description of the antiferroelectric phase transition.