Thermal hysteresis of permeability and transport properties of Cu Substituted Ni0.28Cu0.10+ x Zn0.62– x Fe1.98O4 ferrites

Abstract

Cu Substituted Ni–Cu–Zn ferrites of Composition Ni0.28Cu0.10+ x Zn0.62– x Fe1.98O4 have been prepared by the standard double sintering ceramic technique. The samples were sintered at 1150 C for 3 hours in air. The analysis of XRD patterns indicates that the samples have the single phase cubic spinel structure. The lattice constant is found to decrease linearly with increase in Cu2+ ion concentration obeying Vegard's law. The initial permeability (μ i ) of the Ni–Cu–Zn ferrites exhibits thermal hysteresis when the temperature is cycled from above the Curie temperature Tc to below. The sharp decrease of μ i at T = Tc indicates the sample's good homogeneity. The Curie temperatures, Tc of the studied ferrite samples were determined from the μ i – T curves where the Hopkinson type of peak at the Tc has been observed with the manifestation of a sharp fall in permeability. The Tc is found to increase with increasing Cu-content. DC electrical resistivity increases significantly with the increase of Cu-Content. The ac resistivity (ρ ac ) and dielectric constant (ε′) of the samples are found to decrease with increase in frequency, exhibiting normal ferrimagnetic behavior