From high pressure radial collapse to graphene ribbon formation in triple-wall carbon nanotubes
From high pressure radial collapse to graphene ribbon formation in triple-wall carbon nanotubes
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DOI：
10.1016/j.carbon.2018.09.076
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发表时间：
2019
期刊：
影响因子：
10.9
通讯作者：
S. D. Silva-Santos;R. S. Alencar;R. S. Alencar;A. L. Aguiar;Y. Kim;H. Muramatsu;M. Endo;N. Blanchard;Alfonso San-Miguel;A. G. S. Filho
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文献类型：
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作者：
S. D. Silva-Santos;R. S. Alencar;R. S. Alencar;A. L. Aguiar;Y. Kim;H. Muramatsu;M. Endo;N. Blanchard;Alfonso San-Miguel;A. G. S. Filho
对三壁碳纳米管束在高压下的径向稳定性和不可逆相变进行了实验和理论研究。高达72 GPa）。具有0.83 nm的平均内径和石墨状的管间距离的管，显示出的光学声子的演变证明的径向崩溃的发病。两个外管在29GPa下在222GPa下观察到纳米管开始塌陷，但是最内层管在237GPa下保持稳定。作为模型系统，对较小直径的TWCNTs束进行分子动力学计算，证实了多级压力诱导的塌陷过程。提出了任意壁数碳纳米管的坍塌压力的解析表达式。我们的实验和建模表明，超过60 GPa的压力，不可逆的结构转变的TWCNTs发生。从72 GPa回收的样品的非原位透射电子显微镜表征揭示了碳纳米管的机械失效，其向带状结构演变，如拉曼光谱所证实的。模拟在高压和高温下的管演变表明，形成新的结构，从带状到石墨状，具有不同程度的非晶化或SP3互连。
The radial stability and the irreversible transformation of triple-wall carbon nanotubes (TWCNTs) bundles are investigated at high pressure conditions both experimentally and theoretically (exp. up 72 GPa). The tubes having a mean internal diameter of 0.83 nm and graphite-like intertube distance, show an onset of the radial collapse evidenced by the evolution of optical phonons. The nanotube collapse onset is observed at∼ 22 GPa completes for the two external tubes at∼ 29 GPa, however the innermost tube remains stable up to∼ 37 GPa. Molecular dynamic calculations performed on smaller diameter TWCNTs bundles, as a model system, confirmed the multiple-stage pressure-induced collapse process. An analytical expression for the collapse pressure of carbon nanotubes having an arbitrary number of walls is proposed. Our experiments and modelling show that for pressures beyond∼ 60 GPa an irreversible structural transformation of TWCNTs takes place. Ex situ transmission electron microscopy characterization on the recovered sample from 72 GPa revealed the mechanical failure of carbon nanotubes which evolve towards ribbon-like structures as corroborated by Raman spectroscopy. Modelling the tubes evolution at high pressure and high temperature showed the formation of new structures ranging from ribbon-like to graphite-like with either different degrees of amorphization or s p 3 interlinking.