Electric-Field Induced Tricritical Points in Antiferroelctric Phase Transitions

Abstract

The tricritical point in temperature-electric field phase diagrams was derived for the Landau-type free energy applicable to the antiferroelectric phase transitions. The adopted free energy written in terms of two sublattice polarizations and the applied external field of the symmetry breaking nature contains three possible fourth-order terms and a sixth-order term, thus being capable of producing various types of phase diagrams. Examples of the tricritical points in the phase diagrams are presented for several parameter values.