Tailoring structural and electrical properties in cobalt-doped Ag0.2Na0.8NbO3 ceramics for advanced electronic applications

Abstract

In this work, environment-friendly lead-free polycrystalline ceramic samples of cobalt doped silver sodium niobate with composition Ag_0.2Co_xNa_0.8-xNbO₃ (with x = 0, 0.02, 0.04, 0.06, 0.08) had been prepared by using solid-state reaction technique and effect of Co-doping on dielectric, electrical and ferroelectric properties had been reported. Analysis of X-ray diffraction (XRD) data confirmed the perovskite orthorhombic structure in all specimens with decreasing average crystallite size on increasing Co-content. Scanning Electron Microscopy (SEM) investigation indicated reduction in average grain size from 1.69 μm to 1.29 μm as concentration of cobalt grew from 0 to 0.08. Impedance analyzer had been used to measure dielectric constant and tangent loss over the frequency range from 20 Hz to 10 MHz for temperatures varying from 25⁰ C to 350⁰ C. Both the dielectric constant as well as tangent loss were found to follow a declining trend with the rising frequency as well as rising dopant content. Impedance had also been analyzed to get information on the conduction mechanism and role of grain boundaries over grains had been deduced to be dominant. Ferroelectric behavior of specimens had been assessed through polarization-electric field (P-E) loop measurements that depicted the presence of moderate polarization levels and relatively high coercive field in all specimens making them versatile for advanced electronic applications.