Ugarte D
Institut de Physique Experimentale, Ecole Polytechnique Federale de Lausanne, Switzerland.
Nature. 1992 Oct 22;359(6397):707-9. doi: 10.1038/359707a0.
The discovery of buckminsterfullerene (C60) and its production in macroscopic quantities has stimulated a great deal of research. More recently, attention has turned towards other curved graphitic networks, such as the giant fullerenes (Cn, n > 100) and carbon nanotubes. A general mechanism has been proposed in which the graphitic sheets bend in an attempt to eliminate the highly energetic dangling bonds present at the edge of the growing structure. Here, I report the response of carbon soot particles and tubular graphitic structures to intense electron-beam irradiation in a high-resolution electron microscope; such conditions resemble a high-temperature regime, permitting a degree of structural fluidity. With increased irradiation, there is a gradual reorganization of the initial material into quasi-spherical particles composed of concentric graphitic shells. This lends weight to the nucleation scheme proposed for fullerenes, and moreover, suggests that planar graphite may not be the most stable allotrope of carbon in systems of limited size.
巴克敏斯特富勒烯（C60）的发现及其大量生产激发了大量研究。最近，注意力转向了其他弯曲的石墨网络，如巨型富勒烯（Cn，n>100）和碳纳米管。有人提出了一种普遍机制，即石墨片弯曲以试图消除生长结构边缘存在的高能悬空键。在此，我报告了碳烟颗粒和管状石墨结构在高分辨率电子显微镜中对强电子束辐照的响应；这种条件类似于高温状态，允许一定程度的结构流动性。随着辐照增加，初始材料逐渐重新组织成由同心石墨壳组成的准球形颗粒。这为富勒烯提出的成核方案提供了支持，此外，还表明在有限尺寸的系统中，平面石墨可能不是碳最稳定的同素异形体。
