Piezoelectric properties and depolarization characteristics of BNKLT-0.15/0.075 ceramics doped with different ions

Abstract

Ternary system Bi0.5(Na0.775K0.15Li0.075)0.5TiO3 (BNKLT-0.15/0.075) ceramics doped with Mn2+, Fe3+, Sm3+ ions have been successfully prepared using the high temperature sintering method. The phase structure, piezoelectric properties and depolarization characteristics of the ceramics have been investigated. It is found that Mn2+, Fe3+ ions replace Ti4+ ions and Sm3+ ions replace Bi3+ ions in the BNKLT-0.15/0.075 ceramics. 0.3 mol% Mn2+ doping has a ‘hard’ effect in BNKLT-0.15/0.075 ceramics like it plays the role in lead-contained Pb(Ti,Zr)O3 ferroelectric ceramics. Fe3+ can significantly improve the d33 and kp of the ceramics, while maintaining a slight increment of Qm. However, Sm3+ doping decreases the d33 and kp of the ceramics. The distinct difference of the doping effects on the electrical properties of the ceramics is tightly related to the depolarization process of the ceramics. It is found the thermally stimulated depolarization current (TSDC) of the prepared ceramics have two peaks: one is caused by the disintegration of long-range ferroelectric order into polar nanoregions at Td, and the other peak is induced by the phase transition from R3c to P4bm at Tc-d. The depolarization process of the ceramics has been discussed basing on the TSDC, dielectric characterization and in-situ XRD measurement of the ceramics.