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 (FR) 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 FR-AFT phase field, near the morphotropic phase boundary, dynamic in situ x-ray diffraction showed the continuous field-induced phase transition from the AFT → FR. It is also seen from the changes in the pseudo-cubic (111) diffraction peak that this phase transition is accompanied by movements of non-180o or 90o domains. This resulted in very high field-induced strain of ∼0.8% in these materials. The compositions farther away from the boundary in the AT 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.