Role of ZnO nanoparticle doping on depolarization temperature, piezoelectric and energy harvesting properties of lead-free Bi0.5(Na0.84K0.16)0.5TiO3 ceramics

Abstract

The effects of ZnO nanoparticle doping on the phase formation, phase transition, dielectric, ferroelectric, piezoelectric, and energy harvesting properties of Bi0.5(Na0.84K0.16)0.5TiO3/xZnO or BNKT16/xZnO (with x = 0, 0.02, 0.04, and 0.06 mol fraction) were investigated. The samples were synthesized through a solid-state reaction method. X-ray diffraction results showed that all samples exhibited a single perovskite phase, except the x = 0.06 sample. The depolarization temperature (Td) value, determined by the thermally stimulated depolarization current (TSDC), tended to vanish with increasing ZnO content. The additive also promoted a diffuse transition at Td. High polarization was observed for the x = 0.04 sample: remanent polarization (Pr) = 53.33 μC/cm2 and saturation polarization (Ps) = 55.34 μC/cm2 with large improvements for Pr and Ps values (98 % and 92 %, respectively, as compared to the base composition) and a decrease in the coercive field (Ec). Improvements of piezoelectric coefficients (d33 and g33) were also found for the x = 0.04 sample. This therefore produced an improvement of energy harvesting performance across the samples.