Effect of 60Co gamma irradiation on dielectric and complex impedance properties of Dy3+ substituted Ni-Zn nanoferrites

Nanocrystalline Ni1-xZnxFe2-yDyyO4 (x=0.0, 0.2, 0.4, 0.6, 0.8, 1.0; y=0.0 and 0.1) ferrites were synthesized by combustion method. Ni-Zn-Dy nanoferrites were investigated by X-ray diffraction, scanning electron microscopy, dielectric and impedance properties, before and after 7-irradiation process by Co-60 7-radiation with a dose rate of 310 kGy. The lattice parameter of irradiated samples increased attributed to the conversion of smaller size Fe3+ ions to larger size Fe2+ ions on ionizing effect of gamma radiation. Experimental results reveal that reduction in dielectric constant (epsilon'), loss tangent (tan delta), real (Z') and imaginary (Z '') impedance and increase in sigma(ac) conductivity (sigma(ac)) have been increased with increasing in frequency. It was found that epsilon', tan delta, sigma(ac) increase, Z '' and Z '' reach a maximum value and thereafter decrease with further Zn ion substitution. The values of epsilon', tan delta and sigma(ac) decrease with Dy3+ substitution and enhanced after irradiation. The complex impedance analysis suggesting predominant contribution to conduction was through the grain boundary. (C) 2016 Elsevier B.V. All rights reserved.