Effects of oxide additives on structure and properties of bismuth ferrite-based ceramics

Effects of oxide additives (Bi2O3, MnO2, La2O3, Sm2O3, SnO2, and Nb2O5) on structure and properties of 0.70Bi1.05FeO3–0.30BaTiO3 ceramics were investigated. Their microstructure and electrical properties were dependent on the types and contents of oxide additives. A large piezoelectric constant (d33) of 135–200 pC/N together with a high Curie temperature of 454–504 °C can be obtained in the ceramics with R-C phase boundary. Most of oxide additives can induce the formation of saturated P–E loops and butterfly-shaped S–E curves, while a pinched P–E loop and sprout S-E curve were observed in the Nb2O5-modified ceramics due to a completely suppressed ɛr–T curve and seriously refined grain sizes. There were high bipolar strain values (S = 0.17%) under low driving electric fields for the addition of 0.5%mol Nb2O5. In addition, an enhanced magnetization of Mr = 0.018 emu/g was achieved in the ceramics with 1.0% SnO2 due to the structure distortion and the breaking of spin helix structure.