Compositional induced dielectric relaxation and electrical conduction behavior of samarium modified bismuth sodium titanate ceramic

Abstract

The present manuscript analyzes the dielectric relaxation and conduction behavior of samarium modified sodium bismuth titanate ((Bi(1-x)Smx)0.5Na0.5TiO3) ceramic prepared by solid-state reaction process. The X-Ray Diffraction acknowledges the presence of rhombohedral (R3c) phase in all composition with existence of small secondary phase for composition more than 2% of Sm doping. The dielectric relaxation and conduction mechanism of the compositions were studied through the impedance spectroscopy. The impedance values initially decrease up to doping level of x = 2% and increase with higher doping concentration. The Cole-Cole plot indicates the existence of grain and grain boundary resistance in all compositions. The conductivity enhances up to x = 0.02 and then reduces with doping concentration, and the conductivity spectra fitted with the modified Jonscher's power law indicates that small polaron hopping is the dominant phenomena for conduction in all compositions. The activation energy related to relaxation and conduction was obtained using the Arrhenius equation, and activation energy obtained specifies a reduction in oxygen vacancies with doping. The activation energy suggests that the oxygen vacancies associated with the short-range hopping is responsible for relaxation and doubly ionized oxygen vacancies are responsible for conduction.