Phase structure and piezoelectric properties of Ca- and Ba-doped K1/2Na1/2NbO3 lead-free ceramics

Abstract

Piezoelectric lead-free ceramics, K1/2Na1/2NbO3 (KNN) modified with alkaline-earth (AE) Ca2+ and Ba2+, have been prepared by a conventional solid-state sintering technique. The effect of doping level on sinterability and functional response of KNN was studied. In this way, discs doped with 0 to 2 mol% of Ba2+ and Ca2+ were sintered at 1125ºC for 2h. It was also observed that AE changed drastically the microstructure and grain size of KNN when it was added in concentrations higher than 0.5 mol%. Addition of 0.5mol% of Ba2+ and Ca2+ produced a softening effect in the ferroelectric properties of the material. On the other hand, samples prepared with higher content than 0.5mol% showed poor properties.