Li Yong, Kuang Qifeng, Men Xiaoling, Wang Shenggang, Li Da, Choi Chuljin, Zhang Zhidong
Shenyang National Laboratory for Materials Science, Institute of Metal Research, Chinese Academy of Sciences, 72 Wenhua Road, Shenyang 110016, China.
Korea Institute of Materials Science, 797 Changwondaero, Seongsangu, Changwon 51508, Gyeongnam, Korea.
Nanomaterials (Basel). 2021 Mar 31;11(4):890. doi: 10.3390/nano11040890.
α″-FeN nanomaterials with a shape anisotropy for high coercivity performance are of interest in potential applications such as rare-earth-free permanent magnets, which are difficult to synthesize in situ anisotropic growth. Here, we develop a new and facile one-pot microemulsion method with Fe(CO) as the iron source and tetraethylenepentamine (TEPA) as the N/C source at low synthesis temperatures to fabricate carbon-coated tetragonal α″-FeN nanocones. Magnetocrystalline anisotropy energy is suggested as the driving force for the anisotropic growth of α″-FeN@C nanocones because the easy magnetization direction of tetragonal α″-FeN nanocrystals is along the c axis. The α″-FeN@C nanocones agglomerate to form a fan-like microstructure, in which the thin ends of nanocones direct to its center, due to the magnetostatic energy. The lengths of α″-FeN@C nanocones are ~200 nm and the diameters vary from ~10 nm on one end to ~40 nm on the other end. Carbon shells with a thickness of 2-3 nm protect α″-FeN nanocones from oxidation in air atmosphere. The α″-FeN@C nanocones synthesized at 433 K show a room-temperature saturation magnetization of 82.6 emu/g and a coercive force of 320 Oe.
具有形状各向异性以实现高矫顽力性能的α″-FeN纳米材料在诸如无稀土永磁体等潜在应用中备受关注，而原位各向异性生长的α″-FeN纳米材料很难合成。在此，我们开发了一种新型简便的一锅微乳液法，以Fe(CO)为铁源，四乙烯五胺（TEPA）为N/C源，在低温合成温度下制备碳包覆的四方α″-FeN纳米锥。磁晶各向异性能被认为是α″-FeN@C纳米锥各向异性生长的驱动力，因为四方α″-FeN纳米晶体的易磁化方向沿c轴。由于静磁能，α″-FeN@C纳米锥团聚形成扇形微观结构，其中纳米锥的细端指向其中心。α″-FeN@C纳米锥的长度约为200 nm，直径一端从约10 nm变化到另一端约40 nm。厚度为2 - 3 nm的碳壳保护α″-FeN纳米锥在空气气氛中不被氧化。在433 K合成的α″-FeN@C纳米锥在室温下的饱和磁化强度为82.6 emu/g，矫顽力为320 Oe。
