Frequency dependent dielectric measurements of Cd2+ doped Mn-Zn nano ferrites prepared by sol gel and coprecipitation methods

Abstract

Ferrite powders of Mn-Zn doped with Cd2+ (Mn0.5CdxZn0.5-xFe2O4) were prepared by the sol gel auto- combustion and coprecipitation methods. The effect of Cd2+ doping on the crystalline phase formation was investigated by X-ray diffraction which confirms the spinel structure of prepared samples. Crystallite size found to be lower for samples prepared by coprecipitation method. The samples prepared using coprecipitation, found to be denser as compared to sol gel method. SEM analysis confirmed the nano structure of the prepared samples. Dielectric properties were studied using impedance analyzer (20 Hz – 5 MHz) and RF material analyzer (1 MHz – 3 GHz) respectively. DC electrical measurements showed highly resistive nature of the prepared samples and values are high for samples prepared from sol gel method. Impedance spectroscopic analysis was carried out in the frequency range from 20 Hz to 5 MHz for the prepared samples, showing resistance of grain boundary is higher than grains. Impedance plane plots gave information about the resistive and reactive parts of impedance. The presence of semicircular arcs at lower frequency side, confirms that the high resistance of samples is due to increase in the number of grain boundaries in the nano synthesised samples.