Achieving high piezoelectric performance and enhanced high-temperature resistivity in CaBi2Nb2O9-based textured ceramics

Abstract

CaBi₂Nb₂O₉ (CBN) ceramics exhibit extremely high Curie temperature, but the low high-temperature resistivity and low piezoelectric properties in ceramics limit their application in high-temperature sensors. In this work, the effect of W⁶⁺ donor doping on dielectric, ferroelectric, piezoelectric properties, and resistivity of CBN ceramics were systemically investigated. In the 2 mol% W⁶⁺-doped CBN ceramics (CBNW-2), the piezoelectric constant (from 6.6 to 14.3 pC/N) and the high-temperature resistivity (from 5.8 × 10⁴ to 7.8 × 10⁵ Ω·cm at 600°C) were significantly increased. To further improve the piezoelectric properties, we fabricated textured CBNW-2 with a high Lotgering factor (f) of 97.1% by the templated grain growth method. The textured CBNW-2 ceramics exhibit strong piezoelectric anisotropy. Piezoelectric constant perpendicular to the texture direction (d_33⊥) increases significantly to 23 pC/N, but the piezoelectric constant parallel to the texture direction (d_33∥) is only 0.9 pC/N, resulting in a large d_33⊥/d_33∥ of 25.6. The significant enhancement in d_33⊥ can be attributed to the substantial increase in remnant polarization, which is given by the highly oriented grain arrangement. Besides, d₃₃ after annealing at 900°C remained 21.4 pC/N and the resistivity at 600°C reached 5.7 × 10⁵ Ω·cm. The excellent piezoelectric properties and high-temperature resistivity of the textured CBNW-2 ceramics indicate that it is a promising piezoelectric material for high-temperature applications.