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

点击翻译按钮获取中文摘要

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.