Lead‐reduced Bi(Ni 2/3 Ta 1/3 )O 3 ‐PbTiO 3 perovskite ceramics with high Curie temperature and performance

• Published in: Journal of the American Ceramic Society 2019-03, Vol.102 (3), p.1227-1239
• Main Authors: Pang, Dongfang, Liu, Xitao, Zheng, Jing, Long, Peiqing, Lin, He, Yi, Zhiguo
• Format: Article
• Language: English
• ISSN: 0002-7820; 1551-2916
• DOI: 10.1111/jace.15962

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(Ni 2/3 Ta 1/3 )O 3 ‐PbTiO 3 (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 x BNT‐(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°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  ~ 34.9 μC/cm 2 . Meanwhile, a highest piezoelectric coefficient of d 33  ~ 271 pC/N and a high field piezoelectric strain coefficient of  ~ 560 pm/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.