Preparation and study of Ce2Fe17N3 microflakes with easy-plane anisotropy and high working frequencies

Abstract

Soft magnetic composites (SMCs) are effective as magnetic powder cores in power transformers. Currently, SMCs used in transformers are mostly prepared from NiZn ferrites. One example of this type of material is NiZnCu ferrite, whose working frequency limit is 40 MHz. Above this frequency, its large magnetic loss angle tangent ( tanδm), approximately equal to 0.29 at 100 MHz, seriously impairs the property of transformers. Generally, the magnetic losses in the MHz frequency band result from eddy-current loss, domain wall resonance, and natural resonance, specifically the high natural resonance loss. A way to decrease it is by increasing the resonance frequency (fr). However, the increase in fr is very difficult for the uniaxially anisotropic NiZnCu ferrite due to the Snoek limit. We present a composite of oriented Ce2Fe17N3 microflakes and polyurethane in this letter. Although its true permeability is not as high as that of NiZnCu, the fr reaches 7.5 GHz. As a result, the tanδm at 100 MHz is decreased to 0.015. This indicates that our material has a higher working frequency than NiZnCu and should make fabrication of a 100 MHz transformer possible.