The Control of Permittivity in the Ni-Zn Ferrite Absorber

초록

The variation of magnetic permeability and dielectric constant and their relationship with microwave absorbing properties are investigated in sintered Ni-Zn ferrite. Toroid specimens of (Ni_0.5Zn_0.5O)_1-y(Fe₂O₃)_1+y ferrites are prepared by conventional ceramic processing technique. The large change in magnetic permeability is obsorved by the variation of excess Fe₂O₃ in the Ni-Zn ferrites. The more the iron-excess from y=0.04 to y=0.12, the lower value of both μ_r′and μ_r″ is observed. However dielectric permittivity increases with the increase of the excess Fe₂O₃. The control of permittivity is realized by nitrogen sintering atmosphere and excess Fe₂O₃, respectively.