Conductivity relaxation and oxygen vacancies-related electron hopping mechanism in Pb_1-xLa_x/2Sm_x/2Ti_1-xFe_xO₃solid solutions

Polycrystalline samples of Pb1-xLax/2Smx/2Ti1-xFexO3 (x = 0.20 and 0.30) have been prepared by solid state reaction route. The electrical properties of synthesized samples have been investigated using complex impedance spectroscopy as a function of frequency (100 Hz–1 MHz) within the temperature range of (448–573 K). The fitting of the Nyquist plots reveals that both grain and grain boundary contribute to relaxation and the grain boundaries are more resistive and capacitive than the grains. Modulus analysis shows that relaxation in both the samples is of non-Debye type and temperature independent. The Jonscher`s power law fit to the ac conductivity data confirms that the conduction in the prepared samples is due to the hopping of charge carriers. Long range conductivity type of relaxation is found in both the samples.