Electromagnetic properties of ferrite tile absorber as a function of compaction pressure

Abstract

In this study, the influence of compaction pressure on the electromagnetic properties of Cu-doped NiZn ferrites was investigated. The evolution of the imaginary part - mu '' of the complex magnetic permeability was analysed as a function of compaction pressure of the green bodies, and the relative density and average grain size of the sintered pieces. The results show that mu '' highly depends on the sintered microstructure and that there is threshold value of the average grain size (similar to 20 to 25 mu m) as of which the electromagnetic properties of these kinds of materials significantly worsened. A linear relationship was observed between permeability and grain size, taking into account the two magnetization mechanism contributing to the complex permeability: spin rotation and wall motion, and an empirical polynomial equation has been proposed to satisfactorily predict the evolution of the imaginary part -mu '' of the complex magnetic permeability with a given compaction pressure and sintered relative density.