Achieving high piezoelectric performance and enhanced high‐temperature resistivity in CaBi 2 Nb 2 O 9 ‐based textured ceramics

Abstract CaBi 2 Nb 2 O 9 (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 W 6+ donor doping on dielectric, ferroelectric, piezoelectric properties, and resistivity of CBN ceramics were systemically investigated. In the 2 mol% W 6+ ‐doped CBN ceramics (CBNW‐2), the piezoelectric constant (from 6.6 to 14.3 pC/N) and the high‐temperature resistivity (from 5.8 × 10 4 to 7.8 × 10 5 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, d 33 after annealing at 900°C remained 21.4 pC/N and the resistivity at 600°C reached 5.7 × 10 5 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.