Compressed glassy carbon maintaining graphite-like structure with linkage formation between graphene layers
Compressed glassy carbon maintaining graphite-like structure with linkage formation between graphene layers
复制标题
DOI：
10.1038/s41598-019-43954-5
复制
发表时间：
2019-05
影响因子：
4.6
通讯作者：
Y. Shibazaki;Y. Kono;G. Shen
中科院分区：
文献类型：
--
作者：
Y. Shibazaki;Y. Kono;G. Shen
非晶金刚石是由玻璃碳高压压缩而成，具有抗压强度高等独特性能的新型碳材料。以往的研究将压缩玻璃碳的超高强度归因于从类石墨- esp2键结构到类金刚石- esp3键结构的结构转变。然而，由于实验上的挑战，目前还没有对压缩玻璃碳的键结构进行直接的实验测定。本文利用新研制的双级大体积电池，成功地测定了玻璃碳在高达49.0 GPa的超高压下的对分布函数。结果表明，玻璃碳中的C-C-C键角保持在接近120°，这是esp2键合蜂窝结构的理想角度，高达49.0 GPa。我们的数据清楚地表明，玻璃碳在49.0 GPa时仍保持石墨样结构。相反，石墨烯层间距离随着压力的增加而急剧减小，接近第二近邻C-C距离31.4 GPa以上的值。石墨烯层之间的键可以在如此短的距离内形成，但不是四面体键的形式。压缩玻璃碳的独特结构可能是实现其超高强度的关键。
Amorphous diamond, formed by high-pressure compression of glassy carbon, is of interests for new carbon materials with unique properties such as high compressive strength. Previous studies attributed the ultrahigh strength of the compressed glassy carbon to structural transformation from graphite-likesp2-bonded structure to diamond-likesp3-bonded structure. However, there is no direct experimental determination of the bond structure of the compressed glassy carbon, because of experimental challenges. Here we succeeded to experimentally determine pair distribution functions of a glassy carbon at ultrahigh pressures up to 49.0 GPa by utilizing our recently developed double-stage large volume cell. Our results show that the C-C-C bond angle in the glassy carbon remains close to 120°, which is the ideal angle for thesp2-bonded honey-comb structure, up to 49.0 GPa. Our data clearly indicate that the glassy carbon maintains graphite-like structure up to 49.0 GPa. In contrast, graphene interlayer distance decreases sharply with increasing pressure, approaching values of the second neighbor C-C distance above 31.4 GPa. Linkages between the graphene layers may be formed with such a short distance, but not in the form of tetrahedralsp3bond. The unique structure of the compressed glassy carbon may be the key to the ultrahigh strength.