THE EFFECT OF TEMPERATURE ON THE ELECTRICAL AND DIELECTRIC PROPERTIES OF Mn0.5Ni0.5-xZnxFe2O4 FERRITES

Abstract

MnFe2O4 is one of the iron-based cubic spinel ferrites possessing both magnetic and electrical properties. In this study, Ni 2+ and Zn2+ substituted Mn0.5Ni0.5-xZnxFe2O4 (where x = 0.05 and 0.1) ferrites are prepared by a solid state reaction method. These ferrites are characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared (FT-IR) spectroscopy and complex impedance spectroscopy. X-ray diffraction patterns of the two samples confirms partial substitution of Ni 2+ and Zn+2 ions for Mn2+ ions does not change the basic structure of MnFe2O4. It also provides information about the formation of a single phase spinel structure. The SEM images of the Mn0.5Ni0.5-xZnxFe2O4 (where x = 0.05 and 0.1) ferrites reveals that the material synthesized by solid state reaction method contain agglomerated particles as well as some small particles are observed in addition to the large particles, which is commonly observed from materials prepared by solid state reaction method. FT-IR analysis confirms the formation of vibrational frequency bands associated with the entire spinel structure. The IR spectra of both ferrites show two clear and sharp absorption bands in the range of 414.28 – 561.04 cm−1 . And the two-strong absorption band, which confirms the presence of M-O (Mn, Ni, Zn, Fe) stretching band in both synthesized ferrites. From the impedance analysis, it is found that the real and imaginary parts of impedance values are typically higher at low frequencies and lower at high frequencies. The AC conductivity analysis confirms that the conduction mechanism is due to small polaron hopping and follows Jonscher’s law. Dielectric properties, namely dielectric constant (ε′), are measured at variable temperature using impedance analyzer in the frequency range from 1 kHz to 1 MHz. Both the samples show usual dielectric dispersion which is due to the formation of interfacial polarization.