Electromagnetic and microwave absorption properties of flaky Nd–Ho–Fe particles

The polycrystalline samples NdxHo2−xFe17 (x = 0.0, 0.2, 0.4, 0.6) were prepared by arc melting under high purity argon atmosphere and high energy ball milling method under the protection of ethanol. The influence of the Nd Substitution on phase structure, morphology, saturation magnetization, electromagnetic parameters were investigated by X-ray diffraction, scanning electron microscopy, vibrating-sample magnetometry and vector network analyzer, respectively. The results indicate that the NdxHo2−xFe17 (x = 0.0, 0.2, 0.4, 0.6) powders mainly consist of Ho2Fe17 single phase with different Nd contents. The particle size increases, and saturation magnetization decreases with the increasing Nd content. The minimum absorption peak frequency shifts towards lower frequency region with the increasing amount of Nd substitution. The Nd–Ho–Fe alloys possess the ascendant microwave absorbing properties. The minimum reflection loss of Nd0.2Ho1.8Fe17 powders is −43.46 dB at 6.88 GHz, the frequency bandwidth of RL < −10 dB is 1.68 GHz with the matching thickness of 2.2 mm. And the Nd0.2Ho1.8Fe17 powder was tempered ranging from 50 to 150 °C for 1 h. Compared to the powder without heat treatment, the minimum absorption peak frequency shifts to higher frequency region. And the absorbing frequency bandwidth increases with the increase of tempering temperatures.