Lead-reduced Bi(Ni2/3Ta1/3)O3-PbTiO3 perovskite ceramics with high Curie temperature and performance

With increasing demand of high-temperature piezoelectric devices and growing concern over environment protection, a feasible reduction in lead from lead-based high Curie temperature piezoelectric materials are desperately needed. Herein, a new system of lead-reduced Bi(Ni2/3Ta1/3)O-3-PbTiO3 (BNT-PT) ferroelectric ceramics is fabricated by a conventional solid-state sintering process. The phase transition behaviors as a function of composition and temperature, electrical properties, as well as the domain configurations from a microscopic level have been investigated in detail. The results indicate that crystal structures, phase transition behaviors, and electric properties of BNT-PT ceramics can be affected significantly by the content of BNT counterpart. Dielectric measurements show that xBNT-(1-x)PT ceramics transfer from the normal ferroelectrics to the relaxor ferroelectrics at compositions of x=0.3-0.35. The BNT-PT ceramics exhibit high Curie temperature T-C ranging from 474 to 185 degrees C with the variation in BNT content. The relative dielectric tunability n(r) also rises from only 0.65% for 0.10BNT-0.90PT to 50.23% for 0.40BNT-0.60PT with increasing BNT content. The tetragonal-rich composition 0.30BNT-0.70PT ceramic possesses the maximum remnant polarization of P(r)34.9C/cm(2). Meanwhile, a highest piezoelectric coefficient of d(33)271pC/N and a high field piezoelectric strain coefficient of d33560pm/V are achieved at morphotropic phase boundary (MPB) composition of 0.38BNT-0.62PT. The maximum value of strain 0.31% is obtained in the 0.36BNT-0.64PT ceramic. The largest electromechanical coupling coefficient k(p) is 44.5% for 0.37BNT-0.63PT ceramic. These findings demonstrate that BNT-PT ceramics are a system of high-performance Pb-reduced ferro/piezoelectrics, which will be very promising materials for piezoelectric devices. This study offers an approach to developing and exploring new lead-reduced ferroelectric ceramics with high performances.