ZHENG Laiqi, JIANG Xiangping, CHEN Chao, HUANG Xiaokun, NIE Xin

( Jingdezhen Ceramic Institute, Jingdezhen 333403, Jiangxi, China)

Abstract: Sodium bismuth titanate ceramics have been considered as one of the promising lead-free piezoelectric ceramics to replace Pb(Zr,Ti)O₃ (PZT) based materials, due to their excellent electrical properties. However, their relatively low thermal stability is still an imperative obstacle hindering implementation of these materials for practical applications. Here, we report 0.94Na_0.5Bi_0.5Ti_0.99Cu_0.01O₃- 0.06BaTiO₃ lead–free ceramics with enhanced thermal stability, which was obtained through quenching process. Electrical properties were measured as criteria to evidence the effectiveness of the quenching process, with which the depolarization temperature was increased from 78 °C to 135 °C while high piezoelectric properties (147 pC/N) could be well maintained. By using X-ray photoelectron spectroscopy (XPS) and other analytic methods, it is revealed that the quenching led to an increase in the concentration of oxygen vacancy, giving rise to increased lattice distortion and domain wall pinning effect. As a result, the depolarization temperature was increased.
Key words: quenching; depolarization temperature; oxygen vacancy; lattice distortion