Department of Physics and Astronomy, University of Deleware, DE 19716, USA.
Nanotechnology. 2011 Jul 1;22(26):265605. doi: 10.1088/0957-4484/22/26/265605. Epub 2011 May 17.
In this work, we report a detailed study of the formation of hollow nanostructures in iron oxides. Core/shell Fe/Fe-oxide nanoparticles were synthesized by thermal decomposition of Fe(CO)(5) at high temperature. It was found that 8 nm is the critical size above which the particles have a core/shell morphology, whereas below this size the particles exhibit a hollow morphology. Annealing the core/shell particles under air also leads to the formation of hollow spheres with a significant increase in the average particle size. In the case of the thermally activated Kirkendall process, the particles do not fully transform into hollow structures but many irregular shaped voids exist inside each particle. The 8 nm hollow particles are superparamagnetic at room temperature with a blocking temperature of 70 K whereas the core/shell particles are ferromagnetic.
在这项工作中，我们详细研究了铁氧化物中空纳米结构的形成。通过高温热分解 Fe(CO)(5)合成了核/壳 Fe/Fe-氧化物纳米粒子。结果发现，8nm 是一个关键尺寸，大于该尺寸的粒子具有核/壳形态，而小于该尺寸的粒子则呈现空心形态。在空气中对核/壳粒子进行退火处理也会导致形成空心球体，平均粒径显著增加。在热激活 Kirkendall 过程中，粒子并没有完全转化为空心结构，但每个粒子内部都存在许多不规则形状的空隙。8nm 空心粒子在室温下具有超顺磁性，其阻塞温度为 70K，而核/壳粒子则具有铁磁性。
