Bismuth layered ceramic solid solution with high temperature piezoelectricity endurance and low sintering temperature

- New codoped composite bismuth layered compound (CaBi)1-x(LiMn)xBi6NbTi5O24 ceramics were obtained in a wide sintering temperature range.
- The highest d33 was achieved at a low sintering temperature of 960 oC despite the moderate density.
- The piezoelectricity (d33) was increased about 2 or 3 times of that of the end member while the depolarization temperature is still high.

In this study, we report the electrical performance and structure of Li and Mn codoped Aurivillius type solid solution ceramics with a composition (CaBi)1-x(LiMn)xBi6NbTi5O24 (x = 0-0.04) sintered under different temperatures. The results indicate that single phase structure with a lattice similar to that of the end member CaBi4Ti4O15 could be formed in a wide sintering temperature range for all the compositions investigated. All composite samples show piezoelectric constant values about 2-3 times of that of the designed constituent phase CaBi4Ti4O15 and Bi3TiNbO9. Interestingly, the samples sintered under a relatively low temperature around 960 °C showed the highest d33 and best temperature stability of piezoelectricity. This was attributed to a suppressed Bi evaporation. The results indicated that formation of compound or solid solution system was an effective way in improving the piezoelectric performance. Although a relatively lower Curie temperature (Tc) compared to that of the single phase end member was obtained in the compound system, all the samples still showed a depolarization temperature higher than 500 °C, while the temperature stability below Tc seems to be an issue deserving further investigation.