Gold-Coated Cementite Nanoparticles: An Oxidation-Resistant Alternative to α-Iron

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• 作者：Michael D. Shultz ; Scott Calvin ; Fernando Gonzalez-Jimenez ; Vladimiro Mujica ; Blaine C. Alleluia ; Everett E. Carpenter
• 刊名：Chemistry of Materials
• 出版年：2009
• 出版时间：December 8, 2009
• 年：2009
• 卷：21
• 期：23
• 页码：5594-5600
• 全文大小：825K
• 年卷期：v.21,no.23(December 8, 2009)
• ISSN：1520-5002

文摘

Iron-based nanoparticles are desirable for many applications because of their magnetic properties and inherent biocompatibility. Metallic iron, or α-Fe, is the most sought after because of its high saturation magnetization (up to 220 emu/g). This magnetization in iron nanoparticles is difficult to reach or maintain because of the ease of oxidation, which greatly reduces the magnetization values (90 emu/g or less). Here, we report the synthesis of an iron-based nanoparticle comprising a magnetic cementite core (Fe₃C) that is more oxidation-resistant than α-Fe, an oxide layer, and a gold coating for passivation and easy functionalization. The nanoparticle structure was confirmed via X-ray absorption fine structure and Mssbauer experiments, and morphology was confirmed using transmission electron microscopy. Magnetic characterization yielded a saturation magnetization of 110 emu/g, thus demonstrating cementite as more stable alternative to α-Fe with higher magnetic moments than the iron oxides.