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 degrees C. The remanent polarization, P-r, and the electric coercive field, E-c, increase with a change in the composition x. The electromechanical coupling factors (k(p) and k(33)) and mechanical quality factors Q(m) 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. (c) 2005 Elsevier Ltd. All rights reserved.