Microstructure, electrical properties of CeO2-doped (K0.5Na0.5)NbO3 lead-free piezoelectric ceramics

CeO2-doped K0.5Na0.5NbO3 lead-free piezoelectric ceramics have been fabricated by a conventional ceramic fabrication technique. The ceramics retain the orthorhombic perovskite structure at low doping levels (< 1 mol.%). Our results also demonstrate that the Ce-doping can suppress the grain growth, promote the densification, decrease the ferroelectric-paraelectric phase transition temperature (T (C)), and improve the dielectric and piezoelectric properties. For the ceramic doped with 0.75 mol.% CeO2, the dielectric and piezoelectric properties become optimum: piezoelectric coefficient d (33) = 130 pC/N, planar electromechanical coupling coefficient k (p) = 0.38, relative permittivity epsilon(r) = 820, and loss tangent tan delta = 3%.