Abstract

The Debye model has been developed to investigate the pressure effects on melting point, Debye frequency and Debye temperature of iron metal. The analytical expressions of these thermodynamic quantities have been derived as functions of crystal volume compressibility. The pressure dependence of them is studied based on the well-established equation-of-state which includes the contributions of the anharmonic and electronic thermal pressures. We performed numerical calculations for iron up to pressure 350 GPa and compared with experimental data when possible. Our results show that the Debye frequency and Debye temperature increase rapidly with compression, and beyond 150 GPa they behave like linear functions of pressure. From the pressure-dependent melting point of iron, we deduce the temperatures of the Earth’s inner-outer core boundary (ICB) and core-mantle boundary (CMB). The temperatures of the Earth’s ICB and CMB are predicted lower than 5540(±170) K and about 4060 K, respectively.

Graphical abstract

中文翻译：

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高压下铁的熔点，德拜频率和温度的研究

摘要

开发了德拜模型以研究压力对铁金属熔点，德拜频率和德拜温度的影响。这些热力学量的解析表达式已被推导为晶体体积可压缩性的函数。基于完善的状态方程研究了它们的压力依赖性，其中包括非谐和电子热压力的贡献。我们对压力高达350 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。我们的结果表明，德拜频率和德拜温度随着压缩而迅速增加，超过150 GPa时，它们的行为就像压力的线性函数一样。从铁的压力依赖性熔点来看，我们推导出了地球内外核心边界（ICB）和地幔边界（CMB）的温度。预测地球的ICB和CMB的温度分别低于5540（±170）K和约4060K。

图形概要