Phase evolution and piezoelectric properties of SnO2 doped KNN based piezoceramics

Abstract

The present research focuses on the electrical properties of lead-free piezoceramics (0.985-x)(K0.485Na0.485Li0.03)(Nb0.96Sb0.04)O3-0.015(Bi0.5Na0.5)ZrO3-xSnO2 (KNNLS-BNZ-xSnO2, x = 0.003, 0.006, 0.009, 0.012, and 0.015). This study examines the influence of varying SnO2 doping levels on the microstructure and piezoelectric properties of the ceramics. All the ceramics prepared demonstrate pure perovskite structure without any secondary phases. The Rietveld refinement analysis of XRD data reveals the existence of multiphase evolution around room temperature. The tetragonality (c/a) and cell volume of the ceramics tend to rise with an increase in Sn4+ content, potentially leading to improved ferroelectric characteristics. The optimum values obtained were Curie temperature (Tc) = 395 oC, remnant polarization (Pr) = 21.07 μC/cm2, piezoelectric coefficient (d33)=357 pC/N, piezoelectric voltage constant (g33) = 24 × 10−3 Vm/N, and figure of merit (FOMoff) = 10.34 pm2/N, corresponding to the ceramic doped with x = 0.012 SnO2. The findings indicate that an optimal amount of Sn4+ in the host composition KNNLS-BNZ improves piezoelectric properties by constructing an R-O-T phase boundary near room temperature. This study suggests that the ceramic with x = 0.012 SnO2 exhibits a favorably high Tc coupled with an exceptional energy harvesting capability, making it a suitable candidate for energy harvesting applications.