Structure and electronic properties of carbon onions
Structure and electronic properties of carbon onions
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DOI：
10.1063/1.1360197
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发表时间：
2001-04
影响因子：
4.4
通讯作者：
S. Tomita;T. Sakurai;H. Ohta;M. Fujii;S. Hayashi
中科院分区：
文献类型：
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作者：
S. Tomita;T. Sakurai;H. Ohta;M. Fujii;S. Hayashi
用高分辨透射电子显微镜（HRTEM）、拉曼光谱和电子自旋共振（ESR）研究了由金刚石纳米颗粒制备的球形和多面体碳洋葱。高分辨透射电镜和拉曼光谱研究表明，由于热退火，金刚石纳米颗粒转变为球形洋葱，并最终通过石墨化的进程，成为多面体洋葱。球形洋葱的ESR谱仅显示与结构缺陷相关的悬挂键自旋对应的窄信号。相比之下，对于多面体洋葱，由于传导电子自旋出现了额外的宽信号。这些结果结合以前的电子能量损失谱的结果表明，球形洋葱由小域的石墨sp2片与悬空键缺陷的外围。因此，球形洋葱中的π电子局限于小畴中，而不充当传导电子。在多面体洋葱中，石墨化过程是一个复杂的过程。
Spherical and polyhedral carbon onions prepared from diamond nanoparticles are investigated by high-resolution transmission electron microscopy (HRTEM), Raman spectroscopy, and electron spin resonance (ESR). HRTEM and Raman studies show that, as a result of thermal annealing, diamond nanoparticles are transformed into spherical onions, and finally into polyhedral onions by the progress of graphitization. ESR spectra for spherical onions show only a narrow signal corresponding to dangling bond spins associated with structural defects. In contrast, for polyhedral onions, an additional broad signal due to conduction electron spins emerges. These results combined with previous results of electron energy-loss spectroscopy suggest that the spherical onions consist of small domains of the graphitic sp2 sheets with dangling bond defects in the peripheries. π electrons in spherical onions are thus localized in the small domains and do not act as conduction electrons. In the polyhedral onions, the graphitization pr...