Abstract
The variations of dc conductivities (sigma) of the Sr2-xLixFeMnO6 double perovskite system over a range of temperatures (100-300 K) and for several concentrations (x = 0-0.04) of incorporated Li+ ions are described by the equation sigma = (B/T) exp(-Ea/kT) and show a decrease with decreasing temperature for a given doping. At a given temperature, sigma tends to decrease with increasing x. The derived activation energy shows a gradual increase with x with a range of values which are lower than usually reported. The measured ac impedance was used to extract the relaxation frequencies as a function of composition and temperature.