碳包覆铁纳米颗粒的气相爆轰合成

摘要

Carbon-encapsulated iron nanoparticles were formed using a gaseous detonation method in a mixture of hydrogen and oxygen in which the powder and gaseous forms of ferrocene were used as the raw materials.X-ray diffraction and transmission electron microscopy analysis shows that using either of the two different states of ferrocene yields carbon-encapsulated iron nanoparticles.The encapsulated particles were composed of iron or iron-carbon compounds as the core,and the outer shell was mainly composed of graphitic carbon.The sizes of most spherical nanoparticles varied between 5 and 30 nm.When using gaseous ferrocene in the detonation,the particle size distribution was narrower,the thickness of the shell layer was more uniform,and the particles had a higher sphericity.Using the iron-carbon alloy phase diagram,an analysis of the mechanism for gaseous detonation synthesis of carbon-encapsulated iron nanoparticles was carried out.The magnetic hysteresis loops of carbon-encapsulated iron nanoparticles were analyzed,which exhibit the dual natures of hard magnetic and paramagnetic.%以粉末状与气态二茂铁为原料,以氢气和氧气混合气体为爆轰能源,采用气相爆轰法进行了合成碳包覆铁纳米颗粒实验.XRD和TEM实验结果表明,采用两种不同状态的二茂铁,均得到了纳米碳包覆铁颗粒.该包覆颗粒的组成核为铁或铁碳化合物,外层壳主要由石墨碳组成,大部分球形纳米颗粒尺寸分布于5～30 nm之间.通过对比发现,采用气态二茂铁爆轰时,所得到的碳包铁粒度分布较为集中,壳层厚度比较均匀,且粒子具有较好的球形状.最后结合铁碳合金相图,从热处理角度对气相爆轰合成碳包覆铁纳米颗粒的机理进行了分析,得出产物中α-Fe与Fe3C的形成过程.分析了碳包覆铁纳米颗粒的磁滞回线,其表现出硬磁性与顺磁性双重性质.