Electrical and magnetic properties of Cr3+ substituted nanocrystalline nickel ferrite

The magnetic and electrical properties of Cr3+ substituted nickel ferrite synthesized by wet chemical route have been studied. Particle size measured from x-ray diffraction and from transmission electron microscopy images confirms the nanosize dimension of prepared particles. Magnetic parameters such as coercivity and saturation magnetization are measured from vibrating sample magnetometer. Magnetization, ac susceptibility, electrical resistivity, and Mossbauer measurements were carried out. Electrical properties such as ac resistivity as a function of frequency and dc resistivity as a function of temperature were studied for various Cr3+ substitutions in nickel ferrite. The dielectric properties such as dielectric constant (epsilon') and dielectric loss (epsilon '') were also studied. The dielectric constant and dielectric loss obtained for the ferrites prepared through wet chemical route posses a value lower than that of the ceramically prepared samples of the same composition. The resistivity obtained is higher than that of ferrite prepared by ceramic method. The dc resistivity increases with Cr3+ content x. The observed variation in resistivity is explained by Verwey hopping mechanism. The activation energy derived form the temperature variation in resistivity was found to increase with increasing concentration of Cr3+ ions. (C) 2009 American Institute of Physics. [DOI: 10.1063/1.3176504]