Preparation and Microwave Absorption Properties of La-Ho-Fe Alloys

The La_xHo_2-xFe₁₇ (x=0.0, 0.2, 0.4, 0.6, 0.8) powders were prepared by arc melting and high energy ball milling. The influence of the La substitution on phase structure, morphology, magnetic properties and electromagnetic parameters were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), vibrating-sample magnetometry (VSM) and vector network analyzer (VNA), respectively. The results show that the saturation magnetization increases and the average particle size increases with the increase of La content. The minimum absorption peak frequency shifts towards a lower frequency region with the increase of La content. The minimum reflection loss (RL) of La_0.2Ho_1.8Fe₁₇ reaches –28.72 dB at 8.72 GHz, and the frequency bandwidth of RL<–10 dB reaches about 2.32 GHz with the best matching condition d=1.8 mm. The reflection loss with the thickness ranging of 1.2∼2.4 mm could reach –10 dB, which indicates that the particles are considered as the promising microwave absorbing materials with better absorption properties.