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Structure and Electronic States of Carbon Onions

碳洋葱的结构和电子态

基本信息

批准号：
11440093
负责人：
HAYASHI Shinji
金额：
$ 8.64万
依托单位：
Kobe University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
1999
资助国家：
日本
起止时间：
1999 至 2001
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-11440093/
关键词：
Fullerene Carbon Onions π electrons Graphite Nano-particles Diamond Interstellar Dust ナノカプセル

项目摘要

In this research project, we have performed a systematic study on the structure, and electronic states of carbon onions and carbon nanocapsules. Major results obtained are summarized as :1) Structure and electronic states of carbon onions : By annealing the nanodiamond particles 5nm in size in high vacuum, we could mass produce while spherical onions at around 1700℃ and polyhedral onions above 2100℃. Combining the results of high-resolution TEM, EELS, ESR, Raman spectroscopy and X-ray diffraction, we could conclude that the spherical onions have defective structures rather than the perfect fullerene structure. They possess dangling bonds and localized electronic states. On the other hand, the polyhedral onions are more graphitic and contain de-localized πelectrons.2) Thin films of carbon nanocapsules containing magnetic metallic particles : By means of co-sputtering and post-annealing, we could prepare thin films of carbon nanocapsules containing Ni, and NiCo alloy nanocrystals. By adjusting the alloy composition, the optimum magnetic characteristics could be achieved.3) Carbon onions as a candidate of interstellar dust : We measured the UV-Visible extinction spectra for carbon onions prepared from nanodiamonds and dispersed in pure water. Measured spectra could successfully be reproduced by theoretical calculations, which assume the aggregation of defective onions dispersed in water. Extending the calculation to an isolated spherical onion placed in vacuum, we could obtain an extinction spectrum that agrees very well with a measured interstellar extinction spectrum. This good agreement strongly suggests that the defective onions are one of the components of the interstellar dust.

在本研究项目中，我们对碳洋葱和碳纳米胶囊的结构和电子态进行了系统的研究。1）碳洋葱的结构和电子状态：通过对5 nm大小的纳米金刚石颗粒在高真空中退火，我们可以在1700℃左右批量制备球形洋葱，在2100℃以上批量制备多面体洋葱。结合高分辨TEM、EELS、ESR、拉曼光谱和X射线衍射的结果，我们可以得出球形洋葱具有缺陷结构而不是完美的富勒烯结构的结论。它们具有悬挂键和局域电子态。2）含磁性金属颗粒的碳纳米管薄膜：通过共溅射和后退火的方法，制备了含Ni的碳纳米管薄膜和NiCo合金纳米晶薄膜。通过调整合金成分，可以获得最佳的磁特性。3）碳洋葱作为星际尘埃的候选者：我们测量了由纳米金刚石制备的碳洋葱分散在纯水中的紫外-可见消光光谱。测量光谱可以成功地再现理论计算，假设有缺陷的洋葱分散在水中的聚集。将计算扩展到真空中的孤立球形洋葱，我们可以获得与测量的星际消光光谱非常一致的消光光谱。这种良好的一致性强烈表明，有缺陷的洋葱是星际尘埃的组成部分之一。