Antiferroelectric-like double hysteresis loops in Ag-doped K0.5 Na0.5NbO3 ceramics

Abstract

In this work, we report the effect of Ag+ doping on the microstructure, dielectric, ferroelectric, piezoelectric, and energy storage properties of the K0.5Na0.5NbO3 (KNN) ceramics for which (K0.5Na0.5)(1-x)AgxNbO3 (KNN-xAg) ceramics with x = 0, 0.01, 0.02 and 0.03 were prepared by the conventional solid-state method. The substitution of Ag+ changes the microstructure of KNN from inhomogeneous bimodal grain distribution to homogeneous densely packed grains with an average grain size of 0.5–2.25 μm. The phase transition (TC) of KNN shifts towards the lower temperature side with Ag+ doping. Antiferroelectric-type double PE loops were observed in Ag-doped KNN ceramics at room temperature, which has improved the energy storage and piezoelectric properties of KNN. For ceramics poled at 2 kV/mm for 30 min, a d33 value of ∼149 pC/N and kp ∼0.41 were obtained. These enhanced properties in Ag-doped KNN are due to the occurrence of double polarization hysteresis loops.