Absorption characteristics of NiCuZn ferrite substituted by Mn2O3

The sintered ferrite tile for radio wave absorbers has been required to extend the frequency band and to reduce the thickness. The composition (NiO)11.4(CuO)7.6(ZnO)31.9 (Fe2O3)47.1(Mn2O3)2.0 with a matching thickness of 5.7mm and a frequency band from 30 to 400MHz has been developed by the investigation of sintering conditions. The developed material has higher static susceptibility of rotation magnetization and a narrower interval between the domain wall resonance frequency and the rotation magnetization relaxation time as analysed by complex-permeability spectra. Also the matching thickness is reduced and the absorption band shifts to lower frequencies region compared with the conventional materials. The matching thickness is influenced by the sintered density or Cu segregation in NiCuZn ferrite substituted by Mn2O3.