Dielectric anomaly in Bi₃Ti_1-x(Y_0.5Sb_0.5) _xNbO₉ piezoceramics with high Curie temperature

Bismuth layered material stand out from other piezoelectric materials due to their high Curie temperature (T_c) and are often used in high temperature piezoelectric actuators and capacitors. However, its low piezoelectric coefficient (d₃₃) and dielectric constants (ε′) limit the scope of application of this material. The Bi₃Ti_0.99 (Y_0.5Sb_0.5) _0.01NbO₉ (BTN-1YSb) ceramics by solid state sintering method show improved d₃₃ (8.1 pC/N), dielectric constants (ε′ ∼2051), temperature stability (d₃₃＞8 pC/N at 800 °C) and mechanical quality factor (Q_m ∼ 1834). After Rietveld refinement, it was found that the oxygen element contributed the most to the spontaneous polarization (P_s) enhancement of the piezoelectric material. In addition, three dielectric anomalous peaks are observed for the first time in BTNO-4YSb BTN-3YSb ceramics, which is due to the interaction of point defects with domain walls in a wide temperature range. This advantage can be maximized by tuning the dielectric anomaly peak to provide a more stable d₃₃ at high temperatures. This study analyzes that the contribution of each ion to the piezoelectric properties of BTN-based ceramics and provides a good example for the study of dielectric peaks.