Complex permeability of Fe-deficient Ni–Cu–Zn ferrites

Fe-deficient Ni-Cu-Zn ferrites with composition Ni0.28Cu0.10Zn0.62O(Fe2O3)(1-x), where x = 0.00, 0.02, 0.04, 0.06, and 0.08 were prepared by the double sintering ceramic technique. Real part of the initial permeability mu', Curie temperature T-c, imaginary part of the initial permeability mu '', relative quality factor (Q-factor) of the samples were elaborately discussed as a function of frequency and temperature with increase of Fe-deficiency during the heating and cooling cycles. The temperature dependence of the imaginary part of the complex permeability curves are very interesting to note that there is a peak value of mu '' at particular temperature which corresponds to the T-c because at this temperature the samples might be in complete spin disorder. This reflects that at T-c, a ferrimagnetically ordered state over comes KBT and becomes comparable with mu H-0 where the loss becomes maximum. Results of heating and cooling cycles were found to be very close to each other. The small difference during heating and cooling process might arise due to the thermal hysteresis which is accumulated in this work. In our study, it was noticed that the resonant frequency and T-c increases first with the increase in iron deficiency and decreases after it takes a maximum at x = 0.06.