Dielectric and electromechanical properties of textured niobium-doped bismuth titanate ceramics

Textured Nb-doped bismuth titanate ceramics (Bi₄Ti_3-x/5-Nb_x/5O₁₂, where x = 0.02) were fabricated by templated grain growth. It was found that the use of a fine precursor powder led to enhanced densification of the ceramic, while Nb doping reduced electrical conduction and dielectric loss, which enabled poling at high temperatures and high electric fields. Sintered tapes showed anisotropic dielectric and piezoelectric properties when measured parallel and perpendicular to the casting plane (e.g., the remanent polarization differed by more than a factor of 15 in the two directions). The piezoelectric constant parallel to the casting plane of the tape was approx. 30 pC/N, or approx. 77% of the single-crystal value. Thermal depoling studies demonstrated that high-temperature piezoelectric applications are possible up to approx. 450°C in textured, doped bismuth titanate.