Enhanced high-field strain and reduced high-temperature dielectric loss in 0.6(Bi0.9La0.1)(Fe1−xTix)O3–0.4PbTiO3 piezoelectric ceramics

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0.6(Bi0.9La0.1)(Fe1−xTix)O3–0.4PbTiO3 (BLFT–PT) (x=0, 0.01, 0.02, and 0.04) ceramics were prepared by traditional solid state reaction method. XRD results indicate that BLFT–PT ceramics show the coexistence of rhombohedral and tetragonal phases, and the c/a ratio as well as the fraction of rhombohedral phase decrease with increasing Ti content. Values of the dielectric constant εr, dielectric loss tanθ at 1kHz, Curie temperature Tc, and piezoelectric constant d33 for BLFT–PT ceramics with the composition of x=0.02 were of 682, 0.032, 450°C, and 117C/N, respectively. It is interesting that the maximum strain of BLFT–PT ceramics achieves about 0.2% under the electric field of 120kV/cm, which is twice of that for BLF–PT ceramics without Ti modification and comparable with that of BiScO3–PbTiO3 ceramics. The high temperature dielectric loss was reduced significantly by Ti doping, which was only one tenth of BLF–PT ceramics in the temperature range of 200–400°C. Impedance spectroscopy analysis reflectsthat Ti doping may enhanc the grain resistivity by reduced defect concentration, and thus cause the resistivity of BLFT–PT to increase obviously at elevevated temperatures. These results indicate that BLFT–PT ceramics would be promising candidates for high temperature piezoelectric applications.