Realizing Enhanced Electrical Properties of CaBi2Nb2O9‑Based High-Temperature Piezoceramics by Constructing a Pseudophase Boundary

It is well-known that the regulation of the phase boundary is an efficient strategy to boost the piezoelectric performance of perovskite structure ceramics. However, it is seldomly used in the bismuth-layered structure high-temperature piezoelectric ceramic research field because of the lack of an available morphotropic phase boundary (MPB). In this work, a pseudo-MPB was constructed by the dual introduction of Ce and Cr ions to the CBN ceramic, which remarkably optimized the piezoelectricity and ferroelectricity. Furthermore, the Ce and Cr ions evidently suppressed the oxygen vacancy concentration, leading to improvements in resistivity and thermal stability. Optimized performances with a satisfactory piezoelectric coefficient (d 33 ∼ 17 pC/N) and an elevated resistivity (ρ) of 1.35 × 105 Ω·cm (at 600 °C) were realized in the Ca0.97Ce0.03Bi2Nb1.985Cr0.015O9 ceramic, accompanied by a high Curie temperature (T C ∼ 934 °C) and good piezoelectric thermal stability. These results reveal that the Ca0.97Ce0.03Bi2Nb1.985Cr0.015O9 ceramic could be a prospective piezoelectric material for sensor applications at high temperatures. Moreover, this work provides a feasible strategy for optimizing the piezoelectric performances of the CBN-based ceramics by constructing the pseudo-MPB.