Temperature dependent electrostrictive hysteresis loop in antiferroelectrics

The effects of temperature on electrostrictive hysteresis loops of antiferroelectrics in the tetragonal phase are explored by a thermodynamic model based on Landau theory. Results of numerical simulation show butterfly shaped electrostriction-field hysteresis loops. With the increase in electric-field the strain increases rapidly due to rotations of dipoles and then slowly by field-induced polarization. When temperature decreases the contribution by the rotation increases and moves towards lower field. On the contrary, the field-induced polarization in modulated state has larger contribution to electrostriction. To identify the degree of modulated state a method is proposed that variations of electrostriction and dielectric constant with temperature are related to the degree on an increasing electric field. The simulated results are basically consistent with experimantal results of some antiferroelectrics.