Studies on the magnetic, magnetostrictive and electrical properties of sol-gel synthesized Zn doped nickel ferrite

Zinc doped nickel ferrite i.e., Ni(1-x)ZnxFe(2)O(4) (0 <= x <= 0.6) have been prepared by using sol-gel method. X-ray diffraction of these samples shows the presence of single-phase cubic spinel structure. The room temperature magnetic measurements showed that saturation magnetization (M-s) increases with the substitution of Zn2+ ions up to x = 0.4 and thereafter it begins to decrease, whereas magnetostriction (lambda) value decreases with the addition of Zn2+ in the Ni-Zn ferrite. Dielectric permittivity (epsilon'), dielectric loss tangent (tan delta) and AC conductivity (sigma(AC)) for all the prepared samples have been studied as a function of frequency and composition in the range from 0.05 Hz to 10MHz at room temperature. It has been observed that initially epsilon', tan delta and sigma(AC) decreases with the substitution of Zn2+ up to x = 0.4 and then increases with the further addition of Zn2+ ions. Variation in the slope parameter s with zinc contents indicates the presence of different type of conduction mechanism in different compositions. The dielectric loss curves exhibit relaxation peaks which shift with the addition of Zn contents. The results have been explained on the basis of space charge polarization according to Maxwell-Wagner's two-layer model and the hopping of charges between Fe2+ and Fe3+ as well as between Ni3+ and Ni2+ ions at the octahedral sites. (C) 2011 Elsevier B.V. All rights reserved.