Ferroelectric and piezoelectric properties of bismuth layered-structure ferroelectric (Sr,Na,Bi)Bi2Ta2O9 ceramics

Sodium strontium bismuth tantalate (1 − x)[Na0.5Bi2.5Ta2O9]-x[Sr0.8Bi2.15Ta2O9] (NSBT-x) solid solution ceramics were synthesized by an ordinary firing method. The ferroelectric and piezoelectric properties of the NSBT-x ceramics were characterized. A single phase with the ABi2Ta2O9-type structure was obtained over the entire composition range. The Curie temperature, Tc, linearly decreased with an increase in x from 780 °C (x = 0) to 410 °C (x = 1.0). Well-developed P(polarization)-E(electric field) hysteresis loops were observed for all samples. The observed Pr-values were independent of the composition x. The coercive field, Ec, changed with the composition x and the maximum value of 72 kV/cm was obtained in the NSBT-0.25 ceramics. Superior piezoelectric properties were observed for the NSBT-0.75 ceramics sintered at 1200 °C. The maximum electromechanical coupling factors and mechanical quality factor were kp = 9.0%, k33 = 15.4% and Qm(kp) = 7000, respectively.