Electrical properties of [Ag0.2(K0.52Na0.48)0.8](Nb1−xTax)O3 ceramics

The dependence of electrical properties of [Ag0.2(K0.52Na0.48)0.8](Nb1−xTax)O3 (AKNNT, 0.025≤x≤0.1) ceramics on their structural characteristics was investigated. Sintered specimens had a single phase of perovskite structure with orthorhombic symmetry. The unit-cell volume and B-site bond valence (VB) of ABO3 perovskite structure decreased with Ta5+ content. This decrease induced distortion in the oxygen octahedra. The electromechanical coupling factor (kp) and the piezoelectric constant (d33) of the sintered specimens increased with octahedral distortion. Also, the dielectric constant (εr) increased due to the decrease in B-site bond valence (VB). Effects of Ta5+ content on the remanant polarization (Pr) and coercive field (Ec) as well as mechanical quality factor (Qm) of the sintered specimens were also discussed.