Effect of poling process on piezoelectric properties of sol–gel derived BZT–BCT ceramics

Abstract

Lead free piezoelectric ceramics barium zirconate titanate–barium calcium titanate, [xBZT–(1−x)BCT] (0.48≤x≤0.52), were synthesized by sol–gel method. Calcination of the as-synthesized precursor powders resulted in crystalline powders with single-phase perovskite structure at 700°C, which is significantly lower than that obtained by solid-state reaction. Solid-state sintering at 1450°C resulted in highly dense microstructure with ≥95% of the theoretical density. The effect of electric poling on the piezoelectric properties of the sintered [xBZT–(1−x)BCT] ceramics is studied with varying poling temperatures and poling fields. The results indicated that optimized poling conditions are required in enhancing the piezoelectric properties of [xBZT–(1−x)BCT] ceramics. The morphotropic phase boundary (MPB) composition, 0.5BZT–0.5BCT, showed a high remanent polarization (Pr) of 12.2μC/cm2 and a low coercive field (Ec) of ∼0.14kV/mm. The optimized poling conditions resulted in high piezoelectric charge coefficient d33∼637pC/N, large electromechanical coupling coefficient kp∼59.6%, a large strain of 0.157%, a large piezoelectric voltage constant g33∼29mVm/N for (0.5BZT–0.5BCT) composition. In this report, the excellent piezoelectric properties of the sol–gel derived BZT–BCT ceramics has been analysed and correlated to its structure and poling conditions.