Abstract
The gradual lowering of initial permeability(μi) with increasing frequency is said to be a relaxation phenomenon. The lowering of μi with frequency is improved by CuO substitution for MgO in MgZn ferrite. From the measuring results of the temperature dependence of tan δ, the activation enegy of the relaxation is calculated as approximately 0.43eV. The effect of the parameters in making process on the lattice defects was investigated with special reference to electric conductivity, microstructure and disaccommodation. From the results of time disaccommodation, the change in permeability for MgCuZn ferrites was found to be larger than that of MgZn ferrite. Furthermore, the lowering of permeability with time for both ferrites was regarded as being over 500 hours.
