Enhanced electrical properties of NaBi modified CaBi2Nb2O9-based Aurivillius piezoceramics via structural distortion

Abstract Two-layer structured ferroelectric ceramics, Ca1-x(NaBi)0.5xBi2Nb2O9 (x = 0.0–0.5; CNBN-x), were prepared by solid-state sintering. An artificial pseudo-morphotropic phase boundary was formed by the substitution of Ca with NaBi, and the crystal structure tended to crystallise in the pseudo-tetragonal phase as the increase of NaBi content. Curie temperature (Tc) slightly reduce and remain high value with the increase of NaBi content, which is in the range of 880–935 °C. Moreover, enhanced piezoactivity (d33) and ferroelectricity (Pr) accompanying with decreased dielectric loss can be acquired in NaBi-modified CaBi2Nb2O9. The CNBN-0.1 had the best performance, and its Tc, d33 and Pr was 925 °C, 14.4 pC/N and 6.0 μC/cm2, respectively. Thermal annealing measurement exhibited that the piezoelectric properties of Ca1-x(NaBi)0.5xBi2Nb2O9 had good temperature stability up to 800 °C. Therefore, the NaBi-modified CaBi2Nb2O9 ceramics are perceived to be of promising candidates for high-temperature applications.