A General Method for the Large‐Scale Preparation of Multifunctional Magnetic Sm‐Fe/Co Nanomaterials

Abstract A general method is reported to prepare single crystal Sm‐Fe/Co nanoparticles (NPs) on a tens of grams scale without Ca‐reduction process. The preparation starts with the fabrication of size‐controllable SmH 2 NPs via evaporation‐condensation route, and then Co NPs produced from solvothermal approach are assembled with SmH 2 to form SmH 2 /Co nanocomposites, which are directly annealed at 700 °C for 1.5 h, yielding 160 ± 15 nm SmCo 5 single crystal NPs. Compared with conventional Ca‐reduction process, the method allows more low annealing temperature, and avoids the employment of Ca and the corresponding water washing process, leading to the stable SmCo 5 NPs without obvious oxidation. The SmCo 5 NPs show a large coercivity of 35.4 kOe and high saturated magnetic moment of 86.2 emu g −1 . Furthermore, the method is extended to synthesize Sm 2 Fe 17 NPs, which exhibits good electromagnetic wave absorption performance with a minimum reflection loss of −45.2 dB and the effective absorption bandwidth of 5.61 GHz (9.22–14.83 GHz) at 1.2 mm. More importantly, the method is very suitable to large‐scale synthesis. One synthesis can generate ≈ 42.25 g of SmCo 5 or 43.30 g of Sm 2 Fe 17 NPs, which demonstrates a promising novel strategy to scale up preparation of RE‐Co/Fe NPs for multifunction magnetic applications.