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

Textured Nb-doped bismuth titanate ceramics (Bi4Ti3-x/5-Nbx/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, w hile Nh doping reduced electrical conduction and dielectric loss, which ena bled poling at high temperatures and high electric fields. Sintered tapes s howed anisotropic dielectric and piezoelectric properties when measured par allel and perpendicular to the casting plane (e.g., the remanent polarizati on differed by more than a factor of 15 in the two directions). The piezoel ectric constant parallel to the casting plane of the tape was similar to 30 pC/N, or similar to 77% of the single-crystal value. Thermal depoling stud ies demonstrated that high-temperature piezoelectric applications are possi ble up to similar to 450 degrees C in textured, doped bismuth titanate.