Sintering and electrical properties of Bi4Ti2.95WxO11.9+3x piezoelectric ceramics

Bismuth titanate (BIT) based ceramics doped with different amounts of WO3 were prepared by a chemical route. BIT compound was obtained by hydroxide coprecipitation method and subsequent treatment at 650 °C. The addition of the dopant was performed after calcination by surface doping using an organometallic W-compound in solution. Different amounts of dopant produce different densification behaviour because of changes in the vacancies concentration and secondary phases. Consequently, the microstructure, as well as the electrical properties, are strongly dependent on the dopant concentration. The presence of a minor amount of secondary phase in the W-doped BIT drastically decreases dielectric losses up to high temperatures allowing the polarization of the ceramics and, in consequence, a relatively good piezoelectric response with d33 constants up to 20.