Effect of Na on the structural and electrical properties of lead-free sodium potassium niobate ceramics

Abstract

K1-xNaxNbO3 (where x = 0.48, 0.53, 0.56 and 0.60) (KNN) perovskite structured ferroelectric ceramics were prepared by the solid-state reaction method. X-ray diffraction patterns indicate that single orthorhombic phase was formed for KNN. Dielectric anomalies around 200°C and 370°C were identified as ferroelectric-ferroelectric and ferroelectric-paraelectric transition temperatures for KNN compound. The electrical behavior of KNN ceramics was studied by the help of impedance spectroscopy technique in the different temperature range. The impedance response in KNN ceramics could be resolved into a single contribution, associated with the bulk/grain. The conductivity studies confirm that the activation energies are strongly frequency dependent. A decreasing trend of Z′ with rise in temperature suggests the presence of negative temperature coefficient of resistance (NTCR) in the material in the low frequency region but tends to merge in the high frequency region at almost all temperatures.