Abstract
We have reported the structural and electrical properties of nano particles of Al doped Ni0.2Cd0.3Fe2.5O4 ferrite using X-ray diffraction, dielectric spectroscopy and impedance spectroscopy at room temperature. XRD analysis confirms that the system exhibits polycrystalline single phase cubic spinel structure. The average particle size estimated using Scherrer formula for Lorentzian peak (3 1 1), has been found 5(+/-) nm. The results obtained show that real (epsilon'), imaginary (epsilon '') part of the dielectric constant, loss tangent (tan delta), and ac conductivity (sigma(ac)) shows normal behaviour with frequency. The dielectric properties and ac conductivity in the samples have been explained on the basis of space charge polarization according to Maxwell-Wagner two-layer model and the Koop's phenomenological theory. The impedance analysis shows that the value of grain boundary impedance increases with Al doping. The complex impedance spectra of nano particles of Al doped Ni-Cd ferrite have been analyzed and explained using the Cole-Cole expression. (c) 2008 Elsevier B.V. All rights reserved.