Dielectric and Impedance spectroscopy characterizations of CuO added (Na0,5Bi0,5)0.94Ba0.06TiO3 lead-free piezoelectric ceramics

Abstract : CuO was used to reduce the sintering temperature of (Na0.5Bi0.5)0.94–Ba0.06TiO3 + 0.03 wt.%Sm2O3 (named NBTS) piezoelectric ceramics. Structural/micro-structural, dielectric, and resistive properties of this composition have been studied using impedance spectroscopic method to get better understanding of (i) the electrical conduction and dielectric relaxation mechanism and (ii) microstructure-electrical properties relationship of the materials as a function of temperature and frequency. The XRD patterns reveal the presence of the morphotropic phase MPB (coexistence of tetragonal and rhombohedral phase) for different compositions. Dielectric and complex impedance spectroscopic studies were carried out in a wide frequency (i.e., 102–106 Hz) and temperature (30–500 °C) range. The maximum of permittivity (at transition temperature) was found to decrease with increasing CuO amount in NBTS, but the diffuseness of dielectric peak increases. The nature of frequency dependence of AC conductivity of NBTS follows the Jonscher power law, and calculated DC conductivity follows Arrhenius behavior. The Nyquist plots suggest that the grains only are responsible for the conduction mechanism of the materials. The occurrence of single arc in the complex modulus spectrum of NBTS compositions confirms the single-phase characteristics, and also confirms the presence of non-Debye type of multiple relaxation in the material.