Abstract
We report a comprehensive study of electrical transport properties of stoichiometric (Mg,Ni)-ferrite in the temperature range 77 ≤ T ≤ 300K, applying magnetic field upto 1T in the frequency range 20 Hz-1 MHz. After ball milling of MgO, NiO and ?-Fe2O3 and annealing at 1473K, a (Mg,Ni)-ferrite phase is obtained. The temperature dependency of dc resistivity indicates the prevalence of a simple hopping type charge transport in all the investigated samples. The activation energy decreases by annealing the samples by 1473K. The dc magnetoresistivity of the samples is positive, which has been explained by using wave function shrinkage model. The frequency dependence of conductivity has been described by power law and the frequency exponent ‘s’ is found to be anomalous temperature dependent for ball milling and annealing samples. The real part of the dielectric permittivity at a fixed frequency was found to follow the power law ?/(f,T) ? Tn. The magnitude of the temperature exponent ‘n’ strongly depends on milling time and also on annealing temperature. The dielectric permittivity increases with milling and also with annealing. An analysis of the complex impedance by an ideal equivalent circuit indicates that the grain boundary contribution is dominating over the grain contribution in conduction process.
Highlights
Small ferri-magnetic oxides, technically known as ferrites have attracted considerable attention from a fundamental scientific interest and from a practical point of view for growing applications in the magnetic, electronic and microwave fields [1,2,3,4,5,6,7]
We report a comprehensive study of electrical transport properties of stoichiometric (Mg,Ni)-ferrite in the temperature range 77 ≤ T ≤ 300 K, applying magnetic field upto 1T in the frequency range 20 Hz-1 MHz
Ferrites are extensively used in magnetic recording, information storage, colour imaging, bio-processing, magnetic refrigeration and in magneto optical devices [5,6,7]
Summary
Small ferri-magnetic oxides, technically known as ferrites have attracted considerable attention from a fundamental scientific interest and from a practical point of view for growing applications in the magnetic, electronic and microwave fields [1,2,3,4,5,6,7]. The real part of the dielectric permittivity at a fixed frequency was found to follow the power law /(f,T) Tn. The magnitude of the temperature exponent ‘n’ strongly depends on milling time and on annealing temperature.
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