Tuning effect of silicon substitution on magnetic and high frequency electromagnetic properties ofR2Fe17and their composites

Abstract In this work, we report the tuning effect ofthe Si substitution on the magnetic and high frequency electromagnetic properties of R 2 Fe 17 compounds and their paraffin composites. It is found that the introduction of Si can remarkably improve the magnetic and electromagnetic properties of the R 2 Fe 17 compounds, making the R 2 Fe 17– x Si x -paraffin composites excellent microwave absorption materials (MAMs). By introducing the Si element, their saturation magnetizations decrease slightly, while much higher Curie temperatures are obtained. Furthermore, better impedance match is reached due to the decrease of the high-frequency permittivity e ′ by about 40%–50%, which finally enhances the performance of the microwave absorption. The peak frequency ( f RL ) of the reflection loss ( RL ) curve moves toward high frequency domain and the qualified band width (QB, RL≤–10 dB) increases remarkably. The maximum QB of 3.3 GHz (12.0–15.3 GHz) is obtained for the Sm 1.5 Y 0.5 Fe 15 Si 2 -paraffincomposite ( d =1.0 mm) and the maximum RL of –53.6 dB is achieved for Nd 2 Fe 15 Si 2 -paraffin composite ( d =2.2 mm), both surpassing most of the reported MAMs. Additionally, adistinguished dielectric microwave absorption peak is observed, which further increases the QB in these composites.