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首页> 外文期刊>Nature nanotechnology >Ultrahard carbon film from epitaxial two-layer graphene
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Ultrahard carbon film from epitaxial two-layer graphene

机译：外延两层石墨烯的超空地碳膜

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Atomically thin graphene exhibits fascinating mechanical properties, although its hardness and transverse stiffness are inferior to those of diamond. So far, there has been no practical demonstration of the transformation of multilayer graphene into diamond-like ultrahard structures. Here we show that at room temperature and after nano-indentation, two-layer graphene on SiC(0001) exhibits a transverse stiffness and hardness comparable to diamond, is resistant to perforation with a diamond indenter and shows a reversible drop in electrical conductivity upon indentation. Density functional theory calculations suggest that, upon compression, the two-layer graphene film transforms into a diamond-like film, producing both elastic deformations and sp(2) to sp(3) chemical changes. Experiments and calculations show that this reversible phase change is not observed for a single buffer layer on SiC or graphene films thicker than three to five layers. Indeed, calculations show that whereas in two-layer graphene layer-stacking configuration controls the conformation of the diamond-like film, in a multilayer film it hinders the phase transformation.
机译：原子薄石墨烯表现出令人着迷的机械性能，尽管其硬度和横向刚度差不等于金刚石的硬度。到目前为止，没有实际证明多层石墨烯转化成金刚石的超空地结构。在这里，我们表明，在室温和纳米压痕之后，SiC（0001）上的两层石墨烯表现出与金刚石相当的横向刚度和硬度，与金刚石压痕有抗孔，并且在压痕上显示出导电性的可逆下降。密度函数理论计算表明，在压缩时，双层石墨烯膜变成金刚石状膜，产生弹性变形和SP（2）至SP（3）化学变化。实验和计算表明，在厚度小于三到五层的SiC或石墨烯薄膜上未观察到这种可逆相变化。实际上，计算表明，虽然在两层石墨烯层堆叠配置中，但是在多层膜中控制金刚石状膜的构象，其阻碍相变。

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