Influence of iron substitution on structural and dielectric properties of nano ZnMn<inf>2</inf>O<inf>4</inf>

Abstract

Iron-doped nano ZnMn2O4 (ZnMn2-xFexO4, x = 0, 0.05, 0.15, 0.2) samples were formed using the sol–gel method. Rietveld refinement method revealed small changes in the cell parameters and crystallite size upon doping ZnMn2O4 with Fe. ZnMn2O4 is partially inverse spinel and it exhibited a normal spinel structure as it doped with Fe. The nano nature of the samples was confirmed using the high-resolution transmission electron microscope technique. The changes in the dielectric, complex impedance and complex modulus properties with doping, frequency and temperature were investigated using the complex impedance technique. Maxwell-Wagner model and Koop’s theory were used to explore the dielectric characteristics of the sample. The dielectric constant of 15% Fe-doped ZMO sample is larger than the dielectric of 10% Fe-doped one. The samples exhibited a ferroelectric nature at 60 °C. The a.c. conductivity of 15% Fe-doped sample is slightly higher than that of 10% Fe-doped sample. All doped samples exhibited the overlap large polarons (OLP) model. The doped samples have a single relaxation process. The activation energy of conduction was increased as the amount of Fe doping increased.