Tailoring structure and piezoelectric properties of CaBi2Nb2O9 ceramics by W6+-Doping

Abstract

Calcium bismuth niobate (CaBi2Nb2O9) is a typical bismuth-layer structured piezoelectrics (BLSPs) with a high Curie temperature (TC) of ∼943 °C, but it has low piezoelectric coefficient and high-temperature resistivity which severely limits signal acquisition in the high-temperature piezoelectric vibration sensors. Ion-doping modification is regarded as an effective way to enhance electrical properties. In this work, W6+ donor-doping at Nb5+ site in the CaBi2Nb2-xWxO9 (x = 0, 0.020, 0.025, 0.030, 0.035 and 0.040) piezoelectric ceramics with TC of 931 ± 2 °C were fabricated by the conventional solid-state reaction method. The effects of W6+-doping on crystal structure of CaBi2Nb2-xWxO9 as well as microscopic morphology and electrical properties of ceramics were investigated systematically. The tetragonality, isotropy and electrical properties of the ceramics were enhanced with the introduction of W6+ dopant. It was found that x = 0.025 was the optimal W6+-doping ratio that yielded remnant polarization of 8.0 μC/cm2, electrical resistivity of 3.0 × 106 Ω cm at 600 °C, piezoelectric coefficient (d33) of 14.4 pC/N, and good thermal depoling property. Our work has established a feasible approach to tune the structure of CaBi2Nb2O9 to improve piezoelectric properties for potential applications in high-temperature piezoelectric vibration sensors.