Abstract In this study, nitrogen-doped carbon nanotubes (CN x -NTs) with a 8.4% nitrogen content were investigated under high pressure using Raman spectroscopy as well as X ray diffraction (XRD) with synchrotron radiation. For comparison purpose, high pressure behaviors of carbon nanotubes (CNTs) without nitrogen were studied as well. Two phase transformations were identified in CN x -NTs, which can be assigned to tube shape change from circular to ellipse-like and then to flatten shape. In strong contrast, no obvious phase transition was found in CNTs. In addition to the tube shape change, a high pressure M-carbon phase was also evidenced by XRD. Both CNTs and CN x -NTs showed axial dependent compressibility under high pressure. Furthermore, this study found the CN x -NTs acted more complexly than carbon in other forms such as single wall CNTs, multiwall CNTs, and graphite, suggesting the doping of nitrogen in addition to the wall thickness affect the properties of CN x -NTs under high pressure. Especially the doping of nitrogen could also help to extend the appearance of M-carbon phase to lower pressure range. Finally, the TEM images also show the retrieved CN x -NTs were partially amorphousized, which was believed due to the high pressure M-carbon phase formed at high pressure.

中文翻译：

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使用拉曼光谱和同步加速器 X 射线衍射对氮掺杂碳纳米管进行高压研究

摘要 在这项研究中，使用拉曼光谱以及同步辐射的 X 射线衍射 (XRD) 在高压下研究了氮含量为 8.4% 的氮掺杂碳纳米管 (CN x -NTs)。为了比较，还研究了不含氮的碳纳米管 (CNT) 的高压行为。在 CN x -NTs 中发现了两个相变，这可以归因于管形状从圆形变为椭圆形，然后变为扁平形状。与之形成鲜明对比的是，在 CNT 中没有发现明显的相变。除了管形变化之外，XRD 还证实了高压 M-碳相。CNTs 和 CN x -NTs 在高压下都表现出轴向相关的压缩性。此外，这项研究发现 CN x -NTs 比其他形式的碳更复杂，例如单壁 CNTs，多壁碳纳米管和石墨，表明除了壁厚外，氮的掺杂也会影响高压下 CN x -NTs 的性能。特别是氮的掺杂也有助于将 M-碳相的出现扩展到较低的压力范围。最后，TEM 图像还显示回收的 CN x -NT 是部分非晶化的，这被认为是由于在高压下形成的高压 M-碳相。