Magnetic properties of Cu-Zn ferrites doped with rare earth oxides

Samples of Cu-Zn ferrites doped with different rare earth ions (La, Sm, Nd, Gd, and Dy) are investigated. X-ray diffraction patterns indicated the pre sence of a single spinel phase. The lattice parameter is found to be nearly independent of the doped rare earth ion type. The density is measured and the porosity is calculated for each sample. The magnetization is measured o n toroidal samples using the induction method. The initial permeability mu( i) is measured as a function of temperature at a constant frequency of 10 k Hz and the Curie temperature Te is determined. The variations of magnetizat ion, relative permeability and the initial permeability as a function of th e effective magnetic moment of the doped rare earth ion are discussed.