Excellent microwave absorption of Y₂Fe_15.5Co_0.5Si/paraffin composites by tuning powder particle size

The electromagnetic and microwave absorption properties of Y₂Fe_15.5Co_0.5Si and its paraffin composites have been investigated. It is found that the ball milling time is directly related to the particle size of the powder, which influences the microwave absorption performance and the degree of orientation of the composites. When the particle size of the Y₂Fe_15.5Co_0.5Si powder approaches the grain size, the difference between the in-plane and the out-of-plane anisotropy field of the oriented composite increases. The reflection loss (RL) peak of the oriented composites moves to the low frequency band due to higher complex permeability and complex permittivity values at 0.5–8 GHz. A minimum RL of –52.80 dB, for a thickness of 2.28 mm, at 6.28 GHz is obtained for the Y₂Fe_15.5Co_0.5Si/paraffin composite. The effective absorption bandwidth (EAB: RL ≤ –10 dB) is 5.43 GHz (12.31–17.74 GHz) at 1.12 mm, exceeding many reported microwave absorbing materials. Thus Y₂Fe_15.5Co_0.5Si composites exhibit huge potential for microwave absorption in the Ku band.