Realization of high piezoelectric performance in bismuth titanate niobate via B-site mixed-valance doping

Aurivillius-compound Bi3TiNbO9 (BTN) based high-temperature piezoelectric ceramics doped with mixed-valence cations (Mo1/3Cr2/3)4+ at the lattice B-sites, Bi3Ti1−x(Mo1/3Cr2/3)xNbO9 (BTN-MC100x, x = 0 −0.07), were prepared via the solid-state reaction method. The incorporation of the (Mo1/3Cr2/3)4+ ions into the BTN lattice promotes the preferential growth of grains along the a-axis, making it easier for polarization vector to flip. The optimized composition BTN-MC5 ceramic had a large d33 of 20.3 pC/N with a high TC of 901 °C. It was found that the donor doping effect of (Mo1/3Cr2/3)4+ and the formation of (CrTi′–VO⋅⋅–CrTi′)×defect dipoles contribute to reduce the concentration of oxygen vacancies, thus increasing the resistivity (2.2 ×105 Ω cm at 600 °C). In addition, the d33 of the BTN-MC5 ceramic exhibits an excellent thermal stability against depoling temperature Td. These findings indicate that the BTN-MC5 ceramic is promising candidate for the preparation of high-temperature piezoelectric sensors.