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27 / 2023-04-02 05:54:54
Peculiarity of diamond melting on the Hugoniot
shock compression,,diamond,melting,phase transition
高压物理与材料科学 > 动高压-II
摘要录用
Liang Sun / Laser Fusion Research Center； CAEP
Toshimori Sekine / Osaka University；HPSTAR
The phase diagram of carbon at high pressures and temperatures is crucial for understanding the properties of interiors of ice giants [1-2]. BC8 over ~1 TPa were suggested by theory as the stable post diamond phase with the bc8-diamond-liquid triple point at a pressure of ~1 TPa [3]. Shock Hugoniot data and melting temperature of diamond have been studied by dynamic compressions to TPa pressures [4-5]. However, there is no consensus of the location of the melting curve and the triple point yet, and in-situ X-ray diffraction measurements indicated the high metastability of diamond over 1 TPa [6]. This situation requires further investigations. We try to observe diamond single crystal shocked over 1 TPa using decaying shock technique at SGIII prototype laser facility in China. We employed the standard techniques of line VISAR (for shock velocity (Us) measurement) and SOP (T measurement).The VISAR indicated shock velocity change down to ~20.5 km/s. Us-time and R-time were analyzed in VISAR-SOP data and T- P were calculated during the decaying shock of diamond. The significant differences were indicated from the previous studies [5] on R-Us relation and T-P of shocked diamond to 1.4 TPa by our new experimental results. The T shifts to lower side by ~1000-1500 K and the R shows initial increasing, subsequent slight decreasing, and final increasing to ~0.5. These results can be explained along with the phase relations during the decaying shock from the Hugoniot. When the metastable diamond is compressed further over the metastable extended boundary between diamond and BC8, BC8 can crystallize. Energy input by shock compression at this stage will not effectively increase the amount of melt and hinders the T increase by the crystallization. This corresponds to the triple point. Further compression of diamond will follow the melting curve of BC8 and along the Hugoniot of liquid with high R values to ~0.5. We are simulating to confirm our experimental results. Furthermore, the observed melting behaviors for shocked diamond provides new critical constrain on theoretical calculation and may affect prospect of understanding carbon in the interiors of large ice giants and design of ICF ignition process.

 
重要日期

  • 会议日期

    06月05日

    2023

    至

    06月09日

    2023

  • 04月30日 2023

    提前注册日期

  • 05月01日 2023

    摘要截稿日期

  • 05月01日 2023

    摘要录用通知日期

  • 05月01日 2023

    初稿截稿日期

  • 05月31日 2023

    注册截止日期

主办单位
等离子体物理重点实验室
北京师范大学天文系
承办单位
Matter and Radiation at Extremes期刊
中国工程物理研究院流体物理研究所
北京应用物理与计算数学研究所
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