Crystal structure, dielectric and piezoelectric properties of Ta/W codoped Bi3TiNbO9 Aurivillius phase ceramics

Aurivillius phase Bi3Ti1-xTaxNb1-xWxO12 high temperature piezoceramics were prepared by a conventional solid state reaction method. The crystal structure, dielectric, electrical conduction and piezoelectric properties were systematically studied. Pure or modified Bi3TiNbO9 ceramics revealed the presence of only two-layered Aurivillius phase, indicating that Ta/W doping entered into the B-site of pseudo-perovskite structure and formed solid solutions. The Curie temperature had a strong reliance on the structural distortion. Furthermore, Ta/W dopants act as a donor doping, decrease the number of oxygen vacancies and facilitate the domain wall motion. As a result, Ta/W modifications significantly increase the DC resistivity and piezoelectric properties. Bi3Ti0.98Ta0.02Nb0.98W0.02O12 ceramics possess the optimum d(33) value (similar to 12.5 pC/N) together with a high T-C point (similar to 893 degrees C). Moreover, the resonance -antiresonance spectra demonstrate that the Ta/W-BTN ceramics are indeed piezoelectric in nature at 600 degrees C. The d(33) value of BTTNW-2 ceramic remains similar to 12.2 pC/N after annealing at 700 degrees C. These factors suggest that the BTTNW-based ceramic is a promising candidate for ultra-high temperature sensor applications. (C) 2014 Elsevier B. V. All rights reserved.