Department of Physics, University of Texas at Arlington, Arlington, TX 76019, USA.
Nanotechnology. 2013 Aug 30;24(34):345605. doi: 10.1088/0957-4484/24/34/345605.
We report here a novel synthetic method to prepare monodisperse air-stable FeCo nanoparticles with average sizes of 8, 12 and 20 nm. CoFe2O4 nanoparticles of different sizes were first synthesized by a chemical solution method. The as-synthesized CoFe2O4 nanoparticles were then mixed with ball-milled NaCl powders and heated to 400-500 ° C in forming gas (Ar 93%+H2 7%). The salt powder worked as a separating medium that prevents the CoFe2O4 nanoparticles from agglomerating during the heat treatment while the forming gas reduces the CoFe2O4 nanoparticles to FeCo nanoparticles. Monodisperse FeCo nanoparticles were recovered by dissolving the NaCl in water and subsequently washing with ethanol and acetone. Structural analyses confirmed that FeCo nanoparticles retained the same size as their oxide precursors. The size of the FeCo nanoparticles can be well tuned by controlling the size of the CoFe2O4 nanoparticles. The saturation magnetization of FeCo nanoparticles is size dependent and increases with size.
我们在此报道了一种新颖的合成方法，可制备平均粒径为 8、12 和 20nm 的单分散、空气稳定的 FeCo 纳米颗粒。首先通过化学溶液法合成了不同尺寸的 CoFe2O4 纳米颗粒。然后，将合成的 CoFe2O4 纳米颗粒与球磨的 NaCl 粉末混合，并在形成气体（Ar93%+H27%）中加热至 400-500°C。盐粉末作为分离介质，在热处理过程中防止 CoFe2O4 纳米颗粒团聚，而形成气体则将 CoFe2O4 纳米颗粒还原为 FeCo 纳米颗粒。通过将 NaCl 溶解在水中，并随后用乙醇和丙酮洗涤，回收单分散的 FeCo 纳米颗粒。结构分析证实，FeCo 纳米颗粒保留了与其氧化物前体相同的尺寸。通过控制 CoFe2O4 纳米颗粒的尺寸，可以很好地调整 FeCo 纳米颗粒的尺寸。FeCo 纳米颗粒的饱和磁化强度与尺寸有关，并随尺寸增大而增大。
