Dynamic In Situ X-Ray Diffraction Study of Antiferroelectric–Ferroelectric Phase Transition in Strontium-Modified Lead Zirconate Titanate Ceramics

Abstract

The electric field-induced electromechanical properties of strontium-modified lead zirconate titanate (PSZT) ceramics, at the Zr-rich region of the phase diagram, are investigated by a dynamic in situ x-ray diffraction technique. PSZT compositions with different Zr/Ti ratios are prepared using a tape lamination approach. An experimental setup using Bragg-Brentano parafocusing geometry is used for the in situ x-ray diffraction on samples under a dynamic ac electric field up to their saturation polarization at 0.1 mHz frequency. The results indicated that strains for the compositions in the ferroelectric rhombohedral (F_R) phase field are mostly due to structural changes and non-180° domain movements after coercive field. As a result the experimental longitudinal strains in these materials are not very high (∼0.4%). On the other hand, for the compositions at the F_R-AF_T phase field, near the morphotropic phase boundary, dynamic in situ x-ray diffraction showed the continuous field-induced phase transition from the AF_T → F_R. It is also seen from the changes in the pseudo-cubic (111) diffraction peak that this phase transition is accompanied by movements of non-180^o or 90^o domains. This resulted in very high field-induced strain of ∼0.8% in these materials. The compositions farther away from the boundary in the A_T side showed neither structural changes nor domain movements up to 9 KV/mm. This is commensurate with the low observed strain of 0.03% for these materials.