Investigation of Cr substitution effect on the evolution of La0.67Ca0.2Ba0.13Fe1-xCrxO3 (x=0 and 0.03) electrical properties under frequency and temperature variation

In this study, La0.67Ca0.2Ba0.13Fe1-xCrxO3 (x = 0 and 0.03) powders were prepared by auto-combustion method. The examination of the purity and crystalline structure of the samples by X-ray diffraction showed a cubic structure formed with the Pm (3) over barm space group. Scanning electron microscopy was used to study the morphology and grains size, indicating an agglomeration of nanometric particles. Impedance spectroscopy in the temperature range from 200 to 360 K was used in order to understand the evolution of the electrical behavior of the substituted perovskites. The real and imaginary parts of the impedance were adjusted with two different equivalent circuits. The activation energies extracted from the imaginary part of the impedance, and the electrical conductivity was very closed indicating a transformation of the electrical behavior. This was confirmed by a decrease in the resistance after substitution of Fe cations by Cr ones. AC conductivity studies showed a Jonscher's behavior and a change of conduction process from a succession of NSPT and CBH model to the existence of only CBH one after the substitution.