Large piezoelectric strain observed in sol-gel derived BZT-BCT ceramics

High performance lead (Pb)-free piezoelectric ceramics with excellent piezoelectric properties is in great demand for sensor and actuator applications. Barium zirconate titanate-barium calcium titanate [xBZT -(1 - x)BCT] (x = 0.5) is one such lead free system, which exhibits high piezoelectric properties similar to lead zirconate titanate (PZT). In this study we report the synthesis and characterization of this lead free [xBZT-(1 - x)BCT] (x = 0.5) via wet chemical sol-gel method. Calcination of the BZT-BCT precursor only at 1000 degrees C (against 1300 degrees C reported in the literature) for 4 h resulted in formation of single phase nanoparticles (<50 nm) as confirmed by X-ray diffraction (XRD) and transmission electron microscopy (TEM) studies. Highly dense and homogenous microstructure with 95% of the theoretical density was obtained by solid-state sintering of the green pellets at 1550 degrees C. Remanent polarization (Pr) of 11.55 mu C/cm(2) and relative permittivity of 20,020 at the Curie temperature of 95 degrees C were obtained. Electrically poled BZT-BCT ceramics samples exhibited high piezoelectric charge coefficients, d(33) similar to 530 pC/N, d(33)* similar to 942 pm/V, large electromechanical coupling coefficient k(p) similar to 0.45 and a large strain of 0.15%, which are comparable to those of lead based piezoelectric ceramics. The excellent piezoelectric properties of this sol-gel derived BZT-BCT system has been analyzed and correlated to its structure in this report. (C) 2014 Elsevier B.V. All rights reserved.