Effect of bismuth deficiency on structure and electrical properties of (Na0.5Bi0.5)0.93Ba0.07TiO3 ceramics Original Research Article

(Na0.5Bix)0.93Ba0.07TiO3 (x=0.500–0.492) ceramics were prepared by a citrate method, and the structure and electrical properties of the ceramics were investigated with respect to the amount of Bi deficiency. It was detected that the Bi deficiency had a considerable impact on the crystal structure and microstructure. The inspection of both the temperature dependence of the dielectric properties (free permittivity ε33T/ε0 and dielectric loss tan δ) and the evolution of the polarization–electrical field (P–E) hysteresis loops with measuring temperature suggests that the Bi deficiency served to increase the depolarization temperature (Td). The Bi deficiency led to an increase in the coercive field (Ec) and mechanical quality factor (Qm) together with a decrease in the remanent polarization (Pr) and piezoelectric constants (d33). The variation of the structure and electrical properties with Bi deficiency amount was qualitatively interpreted in terms of the formation of Bi and oxygen vacancies in the Bi-deficient specimens. This research indicates the importance of adequately controlling Bi stoichiometry of (Na0.5Bi0.5)0.93Ba0.07TiO3 ceramics in obtaining the desired ferroelectric and piezoelectric properties.