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

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 degrees domain movements after coercive field. As a result the experimental longitudinal strains in these materials are not very high (similar to 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 degrees or 90 degrees domains. This resulted in very high field-induced strain of similar to 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.