Abstract
Nanocrystalline samples of Ni0.5Mg0.5Fe2-xCrxO4 (0 <= x <= 1.0) have been prepared by citrate-gel auto combustion method. X-ray analysis shows that all the samples are in single phase. The lattice constant 'a' is determined from XRD, decreases with the compositional parameter. The crystallite size estimated to be within the range of 30-35 nm. Impedance spectroscopy techniques have been used to study the effect of grain and grain boundary on the electrical properties of the prepared compound. The impedance data shows only one semicircle corresponding to the grain boundary volume suggesting that the conduction mechanism takes place predominantly through grain boundary volume in the studied samples. The ac conductivity (sigma(ac)) is found to increase with increase in the applied frequency.