Synergistically enhances piezoelectricity and resistivity of high-temperature 0.3Na _0.5 Bi _2.5 Nb ₂ O ₉ –0.7Bi ₃ TiNbO ₉ ceramics by (W,Cr) co-doping

Abstract 0.3Na0.5Bi2.5Nb2O9–0.7Bi3Ti1−x(W1/3Cr2/3)xNbO9 (0.3NBN–0.7BTN–WCx, x = 0–0.06) high Curie temperature piezoceramics with a bismuth layered structure were prepared by a solid-state reaction method. The optimized 0.3NBN–0.7BTN–WC0.04 ceramics possess an enhanced piezoelectric constant (d33 = 20.3 pC/N) with a very high Curie temperature (TC = 845.9 °C). The incorporation of W/Cr ions disrupts the long-range order of the crystal lattice, which induces significant distortion of the [Nb/Ti]O6 octahedral and generates more stable domain structures, contributing to an enhanced piezoelectric response and high Curie temperature. Meanwhile, W6+ donor doping and the formation of (CrTi′−VO⋅⋅) defect dipoles synergistically reduced the concentration of oxygen vacancies, thereby achieving both a high resistivity (ρ = 7.3×107 Ω·cm) and a low dielectric loss (tanδ = 0.057) under high temperature conditions (@500 °C). In addition, the d33 of the 0.3NBN–0.7BTN–WC0.04 ceramics exhibits excellent thermal stability, retaining 93.1% of its initial value (d33 = 18.9 pC/N) after annealing at 600 °C. All results indicate that 0.3NBN–0.7BTN–WC0.04 ceramics can be good candidates for piezoelectric sensor applications in high-temperature harsh environments.