AR-06: High frequency magnetic properties of submicron Fe-Ni-B amorphous particles synthesized by aqueous solution reduction method

Soft magnetic particles with micron-size are widely used in high frequency devices, i.e. inductor, noise suppressor because of high saturation magnetization and flexibility in shape. For the next-generation devices in several GHz range, eddy current becomes serious problem due to low resistivity. One of the effective ways to solve this problem is to reduce the particles size to less than the skin depth. Previously, we reported submicron-sized Fe-B amorphous particles synthesized by aqueous solution reduction method[1]. It found that ferromagnetic resonances were observed in the range of 1 to 3 GHz and their intrinsic permeability were 9-14. Herein, we newly synthesize submicron-sized Fe-B particles doped with Ni and evaluate their structures and magnetic properties. Figure 1 shows SEM image of as-made Fe-Ni-B particles. The particles were non-agglomerative and spherical shape with the median size of approximately 200 nm and the size distribution of 150-250 nm. Similar shape and median size were observed in the annealed particles at 400 for 1 h in Ar ambient. In both samples with and without annealing, the amorphous phase was confirmed by TEM observation. Figure 2 shows the complex permeability (μ' and μ") of the Fe-Ni-B particles composites. μ’ increased from 2 to 2.8 after annealing process. In case of μ’’, broad peaks were observed in both samples. And value of μ’’ was almost zero up to 1 GHz for the annealed sample. This indicates the high frequency magnetic properties were improved by annealing process, which might be attributed to the structure relaxation. In conclusion, these results suggest that submicron-sized Fe-Ni-B particles possess good high-frequency magnetic properties by annealing process.References: [1] K. Murata, T. Miyazaki, H. Masumoto, Y. Endo: T. Magn. Soc. Jpn. (Special Issues)., 5, 1-5 (2021)