Enhanced piezoelectric performance of Cr/Ta non-equivalent co-doped Bi <sub>4</sub>Ti <sub>3</sub>O <sub>12</sub>-based high-temperature piezoceramics
Xuanyu Chen, Ziqi Ma, Bin Li, Yejing Dai
Abstract
In this study, (Cr<sub>1/3</sub>/Ta<sub>2/3</sub>) non-equivalent co-doped Bi<sub>4</sub>Ti<sub>3</sub>O<sub>12</sub> (BIT) ceramics were prepared to solve the problem that high piezoelectric performance, high Curie temperature, and high-temperature resistivity could not be achieved simultaneously in BIT-based ceramics. A series of Bi<sub>4</sub>Ti<sub>3-<em>x</em></sub>(Cr<sub>1/3</sub>Ta<sub>2/3</sub>)<em><sub>x</sub></em>O<sub>12</sub> (<em>x</em> = 0-0.040) ceramics were synthesized by the solid-state reaction method. The phase structure, microstructure, piezoelectric performance, and conductive mechanism of the samples were systematically investigated. The B-site non-equivalent co-doping strategy combining high-valence Ta<sup>5+</sup> and low-valence Cr<sup>3+</sup> significantly enhances the electrical properties due to the decrease in oxygen vacancy concentration. Bi<sub>4</sub>Ti<sub>2.97</sub>(Cr<sub>1/3</sub>Ta<sub>2/3</sub>)<sub>0.03</sub>O<sub>12 </sub>ceramic exhibits a high piezoelectric coefficient (<em>d</em><sub>33 </sub>= 26 pC×N<sup>-1</sup>) and a high Curie temperature (<em>T</em><sub>C </sub>= 687 ℃). Moreover, a significantly increased resistivity (<em>ρ </em>= 2.8×10<sup>6</sup> Ω·cm at 500 ℃) and good piezoelectric stability up to 600 ℃ are also obtained for this composition. All the results demonstrate that Cr/Ta co-doped BIT-based ceramics have great potential to be applied in high-temperature piezoelectric applications.