Characteristics of (Ni_(0.4)Zn_(0.6))Fe_2O_4 Spinel Ferrites Doped with (Ni_(0.8)Zn_(0.2))O Halite Additive

The characteristics of (Ni0.4Zn0.6)Fe2O4 spinel ferrites doped with various amount of (Ni0.8Zn0.2)O halite additives were investigated. The permeability frequency spectra of the doped ferrites (1-x) (Ni0.4Zn0.6)Fe2O4+ x(Ni0.8Zn0.2)O exhibit an anomalous transition at x=0.05, which can be well described by the magnetic circuit model developed by Johnson and Visser. From the experimental data of X-ray diffraction, bulk density, dc electrical resistivity and permeability temperature spectra, the crystallograPhic structure of the doped ferrite for x≤ 0.05 is a pure spinel phase, the presence of a small amount of oxygen vacancies in spinel lattice favors the grain growth and promotes the densification. For x 0.05, the crystallographic structure is a diphasic mixture. The segregation of nonmagnetic y 0.8 (NiyZn1-y)O halite second phase on grain boundary hinders the spinel grain growth and lowers the densification.