Textured high Curie point piezoelectric ceramics prepared by spark plasma sintering

Abstract

The Curie point Tc of ferroelectrics sets the upper temperature limit for their application as piezoelectrics. Some Aurivillius phase and perovskite-like layer structured (PLS) materials are good candidates for high temperature piezoelectric applications because of their high Tc. The Aurivillius phase CaBi2Nb2O9 and PLS Sr2Nb2O7 were densified by ordinary sintering and/or spark plasma sintering (SPS). All of the materials were single phase, and their grains were plate-like. Their density was >95%. The spark plasma sintered ceramics had grain oriented, textured microstructures. The Curie point of CaBi2Nb2O9 was measured as 943±5°C. Ferroelectric switching in CaBi2Nb2O9 was observed at room temperature. The d33 of the textured CaBi2Nb2O9 materials was nearly three times that of ordinary sintered materials. The Curie point of Sr2Nb2O7 was measured as 1327±5°C. Ferroelectric and piezoelectric (2·8 pC N−1) properties were observed for spark plasma sintered textured Sr2Nb2O7 ceramics.