Effect of non-stoichiometry on ferroelectricity and piezoelectricity in strontium bismuth tantalate ceramics

The effect of non-stoichiometry on the ferroelectricity and piezoelectricity of strontium bismuth tantalate, SrBi2Ta2O9, has been studied using ordinarily fired ceramics. Sr1−xBi2+xTa2O9 (x = 0.0–0.3) [SBT(x)] ceramics were prepared by a conventional ceramic technique and sintered at 1200 °C. The remanent polarization, Pr, and the electric coercive field, Ec, increase with a change in the composition x. The electromechanical coupling factors (kp and k33) and mechanical quality factors Qm increase up to around x = 0.2, but decreases at x > 0.2 as the composition x increases. The reduction of the piezoelectric properties at x > 0.2 is associated with the decrease in the electric resistivity of the SBT(x) ceramics. Both the ferroelectric and piezoelectric properties of the SBT(x) ceramics are basically enhanced by the Bi substitution.