Pressure effects on the EXAFS Debye-Waller factor of iron.,Journal of Synchrotron Radiation

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Pressure effects on the EXAFS Debye-Waller factor of iron.
Journal of Synchrotron Radiation ( IF 2.4 ) Pub Date : 2020-08-06 , DOI: 10.1107/s1600577520009741
Ho Khac Hieu ₁ , Nguyen Ba Duc ₂ , Nguyen Van Hung ₃ , Pham Thi Minh Hanh ₄ , Tran Thi Hai ₅

Affiliation

The pressure effects on atomic mean‐square relative displacement characterizing the extended X‐ray absorption fine structure (EXAFS) Debye–Waller factor of iron metal have been investigated based on the Debye model. The analytical expressions of the Debye frequency and EXAFS Debye–Waller factor have been derived as functions of crystal volume compressibility. Based on the well established equation‐of‐state including the contributions of the anharmonic and electronic thermal pressures, numerical calculations have been performed for iron up to a pressure of 220 GPa and compared with experimental data when possible. These results show that the Debye frequency increases rapidly with compression, and beyond 150 GPa it behaves as a linear function of pressure. Meanwhile the mean‐square relative displacement curve drops robustly with pressure, especially at pressures smaller than 100 GPa. This phenomenon causes the enhancement of EXAFS signals at high pressure. Reversely, the increasing of temperature will reduce the amplitude of EXAFS spectra.

中文翻译：

压力对铁的EXAFS Debye-Waller因子的影响。

在Debye模型的基础上，研究了表征金属X射线吸收精细结构（EXAFS）Debye-Waller因子的原子均方根相对位移的压力效应。Debye频率和EXAFS Debye-Waller因子的解析表达式已被推导为晶体体积可压缩性的函数。基于公认的状态方程，包括非谐和电子热压力的贡献，对压力高达220 GPa的铁进行了数值计算，并在可能的情况下与实验数据进行了比较。这些结果表明，德拜频率随压缩而迅速增加，超过150 GPa时，它表现为压力的线性函数。同时，均方根相对位移曲线随着压力而急剧下降，特别是在小于100 GPa的压力下。这种现象导致EXAFS信号在高压下增强。相反，温度升高将降低EXAFS光谱的幅度。

更新日期：2020-08-06

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