Enhanced dielectric, ferroelectric and piezoelectric properties of lead-free (Ba,Ca)(Sn,Ti)O 3 ceramics by optimisation of sintering temperature

Lead-zirconate-titanate [Pb(Zr,Ti)O-3 PZT] crystals possess superior ferroelectric, dielectric and piezoelectric properties. However, due to the toxicity of lead there is a demand for lead-free alternatives. In the present work, we focus on the production of the lead-free (Ba,Ca)(Sn,Ti)O-3 (BCST) ceramics via solid-state synthesis method. BCST ceramics calcined at 1050 degrees C, 1100 degrees C, 1150 degrees C, 1200 degrees C and 1250 degrees C were characterized using XRD analysis which showed that at temperatures above 1150 degrees C the structure was free from impurities. Rietveld refinements confirmed a tetragonal structure with P4mm space group for the material calcined at 1150 degrees C. Scanning electron microscopy image analysis of samples sintered at 1200 degrees C, 1250 degrees C and 1300 degrees C showed an increase in grain size and density with temperature. The material sintered at 1300 degrees C had a higher dielectric constant compared to other ceramics. A larger grain size facilitated high ferroelectric polarisation (3.38 mu C/cm(2)), dielectric constant (6100) and d(33) piezoelectric coefficient (236 pC/N) for the ceramics. This study demonstrates the potential for using lead-free BCST ceramics for device applications, such as piezoelectric actuators, transducers and ultrasonic motors.