Abstract
Abstract
The Curie point T c 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 T c. 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 d 33 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.