中国物理B ›› 2022, Vol. 31 ›› Issue (5): 56101-056101.doi: 10.1088/1674-1056/ac398d

• • 上一篇    下一篇

Temperature dependence of bismuth structures under high pressure

Xiaobing Fan(范小兵), Shikai Xiang(向士凯), and Lingcang Cai(蔡灵仓)   

  1. National Key Laboratory of Shock Wave and Detonation Physics, Institute of Fluid Physics, China Academy of Engineering Physics, Mianyang 621999, China
  • 收稿日期:2021-09-28 修回日期:2021-11-01 出版日期:2022-05-14 发布日期:2022-04-09
  • 通讯作者: Shikai Xiang,E-mail:skxiang@caep.cn E-mail:skxiang@caep.cn
  • 基金资助:
    This work was supported by the CAEP Foundation (Grant No.CX2019002),the Science Challenge Project (Grant No.TZ2016001),and the National Natural Science Foundation of China (Grant Nos.11602251,U1730248,and 11802290).

Temperature dependence of bismuth structures under high pressure

Xiaobing Fan(范小兵), Shikai Xiang(向士凯), and Lingcang Cai(蔡灵仓)   

  1. National Key Laboratory of Shock Wave and Detonation Physics, Institute of Fluid Physics, China Academy of Engineering Physics, Mianyang 621999, China
  • Received:2021-09-28 Revised:2021-11-01 Online:2022-05-14 Published:2022-04-09
  • Contact: Shikai Xiang,E-mail:skxiang@caep.cn E-mail:skxiang@caep.cn
  • About author:2021-11-15
  • Supported by:
    This work was supported by the CAEP Foundation (Grant No.CX2019002),the Science Challenge Project (Grant No.TZ2016001),and the National Natural Science Foundation of China (Grant Nos.11602251,U1730248,and 11802290).

摘要: It is unclear whether there is a liquid-liquid phase transition or not in the bismuth melt at high temperature and high pressure. If so, it will be necessary to confirm the boundary of the liquid-liquid phase transition and clarify whether it is a first-order phase transition. Here, based on x-ray absorption spectra and simulations, the temperature dependence of bismuth structures is investigated under different pressures. According to the similarity of characteristic peaks of x-ray absorption near edge structure (XANES) spectra, we estimate the possible temperature ranges of liquid-liquid phase transition to be 779-799 K at 2.74 GPa and 859-879 K at 2.78 GPa, 809-819 K at 3.38 GPa and 829-839 K at 3.39 GPa and 729-739 K at 4.78 GPa. Using ab initio molecular dynamics (AIMD) simulations, we obtain the stable structures of the bismuth melt at different temperatures and pressures, and calculated their electronic structures. Meanwhile, two stable phases (phase III-like and phase IV-like) of bismuth melts are obtained from different initial phases of bismuth solids (phase III and phase IV) under the same condition (3.20 GPa and 800 K). Assuming that the bismuth melt undergoes a phase transition from IV-like to III-like between 809 K and 819 K at 3.38 GPa, the calculated electronic structures are consistent with the XANES spectra, which provides a possible explanation for the first-order liquid-liquid phase transition.

关键词: liquid-liquid phase transition, bismuth melt, XANES, electronic structure

Abstract: It is unclear whether there is a liquid-liquid phase transition or not in the bismuth melt at high temperature and high pressure. If so, it will be necessary to confirm the boundary of the liquid-liquid phase transition and clarify whether it is a first-order phase transition. Here, based on x-ray absorption spectra and simulations, the temperature dependence of bismuth structures is investigated under different pressures. According to the similarity of characteristic peaks of x-ray absorption near edge structure (XANES) spectra, we estimate the possible temperature ranges of liquid-liquid phase transition to be 779-799 K at 2.74 GPa and 859-879 K at 2.78 GPa, 809-819 K at 3.38 GPa and 829-839 K at 3.39 GPa and 729-739 K at 4.78 GPa. Using ab initio molecular dynamics (AIMD) simulations, we obtain the stable structures of the bismuth melt at different temperatures and pressures, and calculated their electronic structures. Meanwhile, two stable phases (phase III-like and phase IV-like) of bismuth melts are obtained from different initial phases of bismuth solids (phase III and phase IV) under the same condition (3.20 GPa and 800 K). Assuming that the bismuth melt undergoes a phase transition from IV-like to III-like between 809 K and 819 K at 3.38 GPa, the calculated electronic structures are consistent with the XANES spectra, which provides a possible explanation for the first-order liquid-liquid phase transition.

Key words: liquid-liquid phase transition, bismuth melt, XANES, electronic structure

中图分类号:  (X-ray absorption spectroscopy: EXAFS, NEXAFS, XANES, etc.)

  • 61.05.cj
05.70.Fh (Phase transitions: general studies) 81.30.Bx (Phase diagrams of metals, alloys, and oxides) 61.20.Ja (Computer simulation of liquid structure)