Uniform-sized iron oxide nanoparticles obtained from the solution phase thermal decomposition of the iron-oleate complex were encapsulated inside the silica shell by the reverse microemulsion technique, and then thermal treatment under NH₃ to transfer the iron oxide to iron nitride. The transmission electron microscopy images distinctly demonstrated that the as-prepared iron nitride at silica core/shell nanostructures were highly uniform in particle-size distribution. By using iron oxide nanoparticles of 6.1, 10.3, 16.2, and 21.8 nm as starting materials, iron nitride nanoparticles with average diameters of 5.6, 9.3, 11.6, and 16.7 nm were produced, respectively. The acid-resistant properties of the iron nitride at silica core/shell nanostructures were found to be much higher than the starting iron oxide at silica. A superconducting quantum interference device was used for the magnetic characterization of the nanostructure. Besides, magnetic resonance imaging (MRI) studies using iron nitride at silica nanocomposites as contrast agents demonstrated T₂ enhanced effects that were dependent on the concentration. These core/shell nanostructures have enormous potential in magnetic nanodevice and biomedical applications. The current process is expected to be easy for large-scale and transfer other metal oxide nanoparticles.

将油酸铁配合物的溶液相热分解得到的均匀尺寸的氧化铁纳米粒子通过反相微乳液技术包封在二氧化硅壳内，然后在NH ₃下热处理将氧化铁转化为氮化铁。透射电子显微镜图像清楚地表明，在二氧化硅核/壳纳米结构中制备的氮化铁的粒度分布高度均匀。通过使用6.1、10.3、16.2和21.8nm的氧化铁纳米粒子作为起始材料，分别制备了平均直径为5.6、9.3、11.6和16.7nm的氮化铁纳米粒子。发现二氧化硅核/壳纳米结构处的氮化铁的耐酸性能远高于二氧化硅的起始氧化铁。超导量子干涉装置用于纳米结构的磁性表征。此外，使用氮化铁在二氧化硅纳米复合材料中作为造影剂的磁共振成像 (MRI) 研究表明吨₂依赖于浓度的增强效果。这些核/壳纳米结构在磁性纳米器件和生物医学应用中具有巨大的潜力。预计目前的工艺很容易大规模转移其他金属氧化物纳米颗粒。