Complex permeability spectra of polycrystalline Li-Zn ferrite and application to EM-wave absorber

Polycrystalline Li-Zn ferrites were prepared by the usual ceramic sintering method. and their complex permeability spectra were measured. The low-frequency permeability increased with the fraction of Zn ferrite. However, the natural resonance frequency shifted lower as the fraction of Zn ferrite was increased. According to our previous model, the complex permeability spectra were also numerically separated into spin rotation and domain wall motion contributions. For the spin rotational component, which played an important role in the high-frequency region, the static spin susceptibility increased and the spin resonance frequency shifted lower with an increase in the Zn-ferrite fraction. The product values of the static spin susceptibility and the spin resonance frequency, corresponding to the Snoek's product value, took a maximum at a certain fraction of Zn ferrite. This was reflected in the performance of the single-layered electromagnetic wave absorber using the polycrystalline ferrite. (C) 2002 Elsevier Science B.V. All rights reserved.