Shock synthesis, ultrasound measurement, and ab-initio calculation for elastic constants of hexagonal diamond

最近，理论计算研究提出了几种结构的高压相的碳。虽然这些碳的提出的阶段中的一些已经在高压下合成，但它们在常压下没有被观察到。在这项研究中，我们将直径为50 × 10 ^-6 m的铜粉与直径为50 × 10 ^-6 m的高纯石墨粉混合，以控制冲击温升并有效地淬火，并使用粉末枪对其进行冲击压缩。在冲击压缩（18 GPa，2100 K）后从相对密度为0.4的混合物中回收的碳组分的XRD图谱中观察到几个新的峰，这表明在常压下所得碳组分中存在S-碳、R-碳和W-碳相。

Recently, theoretical computational studies have proposed several structures of high-pressure phase of carbon. Although some of these proposed phases of carbon have been synthesized at high pressure, they have not been observed at normal pressure. In this study, we made mixtures of copper powder of 50x10^-6 m diameter with high purity graphite powder of 50x10^-6 m diameter to control shock temperature rise and to quench efficiently, and shock compressed it using powder gun. Several new peaks were observed in XRD patterns of the carbon component retrieved from the mixture of 0.4 relative density after shock compression (18 GPa, 2100 K), which suggest existence of S-carbon, R-carbon, and W-carbon phase in the resultant carbon component at normal pressure.