Piezoelectric, dielectric, and ferroelectric properties of high Curie temperature bismuth layer-structured bismuth titanate-tantalate (Bi<sub>3</sub>TiTaO<sub>9</sub>)

Abstract

Piezoelectric materials have been extensively employed in numerous devices. With the rapid development of modern information technology, the high temperature piezoelectric materials that can work in extreme environments are in great demand. Therefore, it is urgent to investigate piezoelectric materials with high Curie temperature and strong piezoelectric performance. This paper reports the significantly improved piezoelectric properties of high temperature bismuth titanate-tantalate (Bi<sub>3</sub>TiTaO<sub>9</sub>, BTT) polycrystalline ceramics. In this work, the rare-earth cerium ions modified Bi<sub>3</sub>TiTaO<sub>9</sub> piezoelectric ceramics are prepared by the conventional ceramic technique. The introduction of Ce ions significantly enhances the piezoelectric performance of BTT ceramics. The BTT-6Ce (BTT+0.6 wt.% CeO<sub>2</sub>) exhibits optimized piezoelectric properties with a piezoelectric coefficient <i>d</i><sub>33</sub> of 16.2 pC/N, which is four times the value of unmodified BTT (<i>d</i><sub>33</sub>~4.2 pC/N). The dielectric and ferroelectric measurements indicate that Ce ions remarkably reduce the dielectric loss tan<i>δ</i> and increase polarizations, which are beneficial to the piezoelectric properties. The BTT and BTT-6Ce (<i>x</i> = 0.6) ceramics each have a high Curie temperature <i>T</i><sub>C</sub>: ~890 ℃ and 879 ℃, respectively. The coercive field <i>E</i><sub>c</sub> of BTT and BTT-6Ce ceramics are 53.8 kV/cm and 57.5 kV/cm, respectively, while the remnant polarizations <i>P</i><sub>r</sub> of BTT and BTT-6Ce ceramics are 3.4 μC/cm<sup>2</sup> and 5.4 μC/cm<sup>2</sup>, respectively, at a frequency of 1 Hz, temperature of 180 ℃, and drive field of 110 kV/cm. The thermal annealing measurements indicate that the BTT ceramics still possess stable piezoelectric properties after being annealed at 800 ℃. The results exhibit that the cerium-modified BTT ceramics are good materials for high temperature applications.