Effect of Zn substitution on structural, magnetic and electric transport properties in inverse spinel NiFe2O4.

In the present investigation, we report a comparative study of structural, magnetic and electric transport properties in bulk NiFe 2 O 4 and Ni 0.7 Zn 0.3 Fe 2 O 4 ceramics. The materials were synthesized by solid state reaction method. X-ray diffraction analysis confirmed the cubic spinel structure of the ferrite samples belonging to the Fd 3 ‾ m space group. The structural analysis of the ceramics was comprehensively evaluated from Rietveld refinements of the XRD data and Raman studies. An increased grain size in the Ni 0.7 Zn 0.3 Fe 2 O 4 microstructure was noticed due to Zn substitution. Both structural and microstructural modifications led to a significant change in the magnetic and electric properties of the Ni 0.7 Zn 0.3 Fe 2 O 4 ceramic. A large increase in saturation magnetization with decreased coercivity was noticed in the Ni 0.7 Zn 0.3 Fe 2 O 4 system due to Zn substitution. DC resistivity was observed to decrease in the Zn-substituted nickel ferrite ceramic due to increased grain size and larger electron hopping between Fe3+ and Fe2+ ions, as verified by the XPS analysis. Further, a remarkable dielectric relaxation has been observed in the Ni-Zn ferrite owing to greater charge hopping and interfacial polarization. Complex impedance spectra of Ni 0.7 Zn 0.3 Fe 2 O 4 revealed evidence of surface polarization contribution with grain and grain boundary effect on the electric transport properties. [ABSTRACT FROM AUTHOR]