Microstructural investigation of magnetic CoFe2O4 nanowires inside carbon nanotubes by electron tomography.
Microstructural investigation of magnetic CoFe2O4 nanowires inside carbon nanotubes by electron tomography.
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DOI：
10.1021/nl072714e
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发表时间：
2008-03
期刊：
影响因子：
10.8
通讯作者：
O. Ersen;S. Bégin;M. Houllé;J. Amadou;I. Janowska;J. Greneche;C. Crucifix;C. Pham‐Huu
中科院分区：
文献类型：
--
作者：
O. Ersen;S. Bégin;M. Houllé;J. Amadou;I. Janowska;J. Greneche;C. Crucifix;C. Pham‐Huu
采用温和化学合成的方法，在多壁碳纳米管通道内铸造出了cofe2o4磁性纳米线。对这些纳米线进行了详细的研究，主要使用电子断层扫描技术；这项研究从空间组织和形成纳米线的单个颗粒的尺寸分布以及其残余孔隙度方面提供了它们的微观结构的完整表征。特别是，我们已经表明，cofe2o4单晶颗粒的大小与颗粒在纳米管内的位置密切相关，即小颗粒靠近管尖（5 nm），大颗粒在管通道内（15 nm）。由于CoFe 2O4超顺磁弛豫的理论临界尺寸估计在4-9 nm范围内，3D-TEM得到的尺寸分布与Mossbauer研究一致，表明纳米线内部存在两种不同的磁性成分。我们还表明，采用这种制备方法和纳米管的内径，cofe2o4纳米线沿管呈连续结构，剩余孔隙率为38%，填充率仅为50%，这些参数对该体系的磁性行为有重要影响。
Magnetic nanowires of CoFe 2O4 were casted inside the channel of multiwall carbon nanotubes by mild chemical synthesis. A detailed investigation of these nanowires was performed using mainly the electron tomography technique; this study provides a complete characterization of their microstructure in terms of the spatial organization and the size distribution of individual particles forming the nanowire as well as its residual porosity. In particular, we have shown that the size of the CoFe 2O4 monocrystalline particles is closely dependent on the location of the particle within the nanotube, i.e., small particles close to the tube tip (5 nm) and bigger particles inside the tube channel (15 nm). As the theoretical critical size for superparamagnetic relaxation in CoFe 2O4 is estimated within the range of 4-9 nm, the size distribution obtained by 3D-TEM agrees with the Mossbauer study that suggests the presence of two different magnetic components inside the nanowire. We have shown also that, by using this preparation method and for this internal diameter of nanotube, the CoFe 2O4 nanowire exhibits a continuous structure along the tube, has a residual porosity of 38%, and can fill the tube at only 50%, parameters which influence in a significant manner the magnetic behavior of this system.