在极端条件下研究Fe的相位过渡,采用基于机器学习力场的无声方法
Feng-Ning Xue1, Yong-Chao Wu1, Yong Lu2
1State Key Laboratory of Explosion Science and Safety Protection, Beijing Institute of Technology, Beijing, 100081, China. shao_jianli@bit.edu.cn.
Physical chemistry chemical physics : PCCP
|March 27, 2025
概括
固体铁 (Fe) 在高压下从以体为中心的立方体 (bcc) 转变为六角密封 (hcp). 取决于温度的无声效应增加了过渡压力,横向声学 (TA1) 声声模式驱动了变化.
科学领域:
- 材料科学 材料科学 材料科学
- 凝聚物质物理学 凝聚物质物理学
- 计算化学计算化学
背景情况:
- 在极端条件下,固体铁 (Fe) 的相变机制尚未完全理解.
- 研究Fe的结构和动态特性对于了解其在高压和高温下的行为至关重要.
研究的目的:
- 系统地研究固体铁的相变过程和动态机制.
- 为了确定温度和压力对Fe的相变的影响.
- 阐明声非和性在Fe的相变中的作用.
主要方法:
- 机器学习力场分子动力学 (MD) 模拟.
- 无音声的计算方法.
- 计算不同Fe相 (bcc,hcp,fcc) 的赫尔姆霍尔茨和吉布斯自由能量.
主要成果:
- 在0K时,Fe在13.83GPa时从bcc过渡到hcp. 这种过渡压力在1000K时增加到17.20 GPa,这是由于温度的不和效应.
- 在bcc到hcp过渡期间,Fe的面中心立方 (fcc) 阶段被确定为转移稳定.
- 横向声学 (TA1) 声分支表现出软化,表明bcc阶段的动态不稳定性和强烈的声不和性,通过中间fcc阶段促进bcc到hcp的过渡.
结论:
- 这项研究提供了对铁在极端条件下的bcc → hcp相过渡的详细了解.
- 这些发现支持对Fe的两步相变的实验观测.
- TA1声模式的确定的作用为管理相位过渡的动态机制提供了洞察力.
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