Textured high Curie point piezoelectric ceramics prepared by spark plasma sintering

摘要

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 CaBi_2Nb_2O_9 and PLS Sr_2Nb_2O_7 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 CaBi_2Nb_2O_9 was measured as 943 + - 5°C. Ferroelectric switching in CaBi_2Nb_2O_9 was observed at room temperature. The d_(33) of the textured CaBi_2Nb_2O_9 materials was nearly three times that of ordinary sintered materials. The Curie point of Sr_2Nb_2O_7 was measured as 1327±5°C. Ferroelectric and piezoelectric (2 ? 8 pC N~(-1)) properties were observed for spark plasma sintered textured Sr_2Nb_2O_7 ceramics.