Enhancement of Resistivity and Piezoelectric Coefficient of CaBi 2 Nb 2 O 9 Ceramic by Microstructure and Defect Modulation

CBNO ceramic-based piezoelectric sensors are of considerable interest owing to their elevated operational temperatures. A multiscale modulation strategy has been developed for increasing high-temperature resistivity and piezoelectric properties of calcium bismuth niobate (CaBi₂Nb₂O₉, CBNO) ceramics. Fine grains and nanoscale ferroelectric domains are achieved in Ca_0.92(Li_0.5Sm_0.5)_0.08Bi₂Nb_2-xTa_xO₉ (abbreviated as (CLS)BN-10xT, x = 0, 0.2, 0.4, 0.6, 0.8) ceramics by composition and defect compensation. The optimization of ferroelectric properties and the decrease of both intrinsic defects and carrier migration gives rise to superior resistivity, high-temperature stability, and piezoelectric coefficient. Consequently, a resistivity of 7.89 × 10⁶ Ω·cm is achieved at 600 °C, maintaining 1.71 × 10⁶ Ω·cm at 650 °C for (CLS)BN-6T ceramic. This is comprehensively superior to that of the most known CaBi₂Nb₂O₉-based ceramics. Notably, the ceramics show good performance in terms of temperature stability as well as a piezoelectric coefficient (d₃₃ = 17.1 pC/N). This work provides a solid technical foundation for the development of high-performance, high-temperature acceleration sensors.