(Bi0.5Na0.5)TiO3 ferroelectric ceramics: Achieving high depolarization temperature and improved piezoelectric properties

• Published in: Journal of the European Ceramic Society Vol. 40; no. 15; pp. 5392 - 5401
• Main Authors: Han, Jihui, Yin, Jie, Wu, Jiagang
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.12.2020
• Subjects: (Bi1/2Na1/2)TiO3; Depolarization temperature; Piezoelectric ceramics; Piezoelectric constant; Temperature stability; Piezoelectric constant; Depolarization temperature; Piezoelectric ceramics; (Bi1/2Na1/2)TiO3; Temperature stability
• ISSN: 0955-2219; 1873-619X
• DOI: 10.1016/j.jeurceramsoc.2020.07.006

(Bi1/2Na1/2)TiO3-based materials have received much attention due to large electro-strain and high piezoelectric constant (d33), but the tough issue is that the existence of inherent depolarization temperature (Td) limits the temperature stability and application temperature range. Previously, reports about the formation of BNT/oxide (i.e., ZnO, Al2O3) composites thought that Td can be deferred to a higher temperature and then thermal depolarization improves. However, the deferred Td of BNT/oxide composites is limited, accompanied by a low d33. Here, we design the {[Bi0.5(Na0.8K0.2)0.5]1-xPbx}TiO3 ceramics, leading to a big shift of Td from 77 ℃ to 390 ℃. Large d33 (140 pC/N) and high Td (∼263 ℃) can be simultaneously achieved for the sample with Pb=0.05, and Td could be further deferred higher (390 ℃) for Pb=0.20. The off-centre displacement of Pb induced by Pb-O hybridization in the PbO12 polyhedron and ferroelectric order stabilized by the addition of Pb can provide the driving force to strengthen the ferroelectric order, and then promote the thermal stability.