Fabrication and characterization of Ti modified BiFeO3-PbTiO3 high temperature piezoelectric ceramics

Solid solutions of 0.65(Bi_0.94La_0.06)(Fe_1-xTi_x)O₃-0.35PbTiO₃ (BLFT-PT) for 0.01 ≤ x ≤ 0.06 were fabricated using the mixed oxide method. XRD results indicated that BLFT-PT has a singe perovskite structure and Ti can promote the formation of tetragonal structure. The effects of Ti substitution on dielectric properties of BLFT-PT were studied at frequencies from 10² to 10⁶ Hz over a temperature range from 30 to 650°C. The results indicate that Ti modification can reduce the room temperature dielectric loss at the low frequencies and increase the dielectric constant of BLFT-PT. The Curie temperature of BLFT-PT for x=0.03 is 525°C, which is about 140°C higher than that of PZT ceramics. The impedance spectroscopy study reveals that the high temperature conduction of BLFT-PT may be attributed to the motion of oxygen vacancies within the material. Our results indicate that BLFT-PT is a good candidate high-temperature piezoelectric ceramic with reduced lead content.