The impedance, dielectric and piezoelectric properties of Tb4O7 and Tm2O3 doped KNN ceramics

Abstract

Rare earth (RE) elements (Tb, Tm) doped K0.5Na0.5NbO3 (KNN) lead-free ceramics were fabricated using conventional solid-state reaction method. All samples with dominating orthorhombic phase are well developed. The effects of Tb and Tm on impedance, dielectric and ferroelectric properties are systematically studied. There are relaxation-like features of the ceramics after the doping of RE elements. Conduction processes were affected by defect, especially in KNN-Tb ceramics, in the higher temperature region. The doping of Tb and Tm increases density, remnant polarization and the piezoelectric constant of the KNN ceramics due to the effect of donor doping. The overall analysis has confirmed the significance of RE elements (Tb, Tm) doping in KNN and shows that it is a promising candidate as lead-free piezoelectric ceramics.