Enhanced piezoelectric properties and low electrical conductivity of Ce-doped Bi7Ti4.5W0.5O21 intergrowth piezoelectric ceramics

Abstract

New types of Ce-doped CexBi7-xTi4.5W0.5O21 (BTW-BIT-xCe) Aurivillius intergrowth ceramics with high Curie temperatures were synthesized to improve the piezoelectric performances as well as the conduction behaviour, and these ceramics exhibit great potential for high-temperature lead-free piezoelectric applications. The crystal structure, electrical properties and conduction behaviour of BTW-BIT-xCe samples were analysed thoroughly. The XRD patterns combined with Rietveld refinements of the patterns showed that the crystal structure transformed from orthorhombic structure towards pseudo-tetragonal structure with increasing CeO2 dopant, indicating that a higher symmetry was obtained. The dielectric properties of Ce-doped samples were improved, accompanied by a significant drop in the dielectric loss and a slight decreased Curie temperature (705 °C–683 °C). An enhanced piezoelectric constant d33 of 25.3 pC/N was obtained in BTW-BIT-0.12Ce, which may be attributed to a common decrease in the electrical conductivity and coercive field. Besides, a low electrical conductivity of 2 × 10-6 S/cm at 540 °C was achieved in the same component owing to a decreased concentration of the oxygen vacancies, which was verified by analyses on XPS spectra. The above results indicate that Ce-doped BTW-BIT samples have great development potential for high temperature piezoelectric applications.