Sol-gel synthesis of nanocrystalline Zn1-xNixFe2O4 ceramics and its structural, magnetic and dielectric properties

Zn1-xNixFe2O4 (0.0 a parts per thousand currency sign x a parts per thousand currency sign 1.0) nanoparticles are prepared by sol-gel method using urea as a neutralizing agent. The evaluation of XRD patterns and TEM images indicated fine particle nature. The average crystallite size increased from 10 to 24 nm, whereas lattice parameters and density decreased with increasing Ni content (x). Infrared spectra showed characteristic features of spinel structure along with a strong influence of compositional variation. Magnetic measurements reveal a maximum saturation magnetization for Zn0.5Ni0.5Fe2O4 (x = 0.5); however, reduced value of magnetization is attributed to the canted spin structure and weakening of Fe3+(A)-Fe3+(B) interactions at the surface of the nanoparticles. Impedance analysis for different electro-active regions are carried out at room temperature with Ni substitution. The existence of different relaxations associated with grain, grain boundaries and electrode effects are discussed with composition. It is suggested that x = 0.5 is an optimal composition in Zn1-xNixFe2O4 system with moderate magnetization, colossal resistivity and high value of dielectric constant at low frequency for their possible usage in field sensor applications.