Electrical conductivity and dielectric analysis of La0.75(Ca,Sr)0.25Mn0.85Ga0.15O3 perovskite compound

In the present study the tool of impedance spectroscopy was utilized to characterize dielectric behavior of AMn(0.85)Ga(0.15)O(3) (A = La0.75Ca0.08Sr0.17) composition synthesized by the solid-state reaction. The complex impedance has been investigated in the temperature range 100-360 K and in the frequency range 40 Hz-2 MHz. The Z' and Z '' versus frequency plots were found to exhibit a semi-circular arc described by an electrical equivalent circuit. The conductivity spectra have been investigated by the Jonscher universal power law: sigma(omega) = sigma(dc) + A omega(n), where omega is the frequency of the ac field, and n is the exponent. The activation energy obtained both from dc conductivity and modulus spectrum are very similar, and hence the relaxation process may be attributed to the same type of charge carriers. (C) 2012 Elsevier B.V. All rights reserved.