W is a ubiquitous refractory metal with numerous potential applications, but its high-pressure melting behaviors remain controversial. Some physicists suggest that the problem may be addressed by including the contribution of vacancies. However, their ideas stay unverified due to the lack of information about crystallographic defects in harsh environments. Herein, the statistical moment method is enhanced to illuminate how vacancies form and impact the melting properties of W. Our anharmonic calculations indicate that the well-known Arrhenius law fails to model the proliferation of vacancies during isobaric heating. Besides, the Gibbs energy of vacancy formation will be severely underestimated if the contribution of external work is neglected during isothermal squeezing. After scrutinizing both temperature and pressure effects, we conclude that the equilibrium vacancy concentration of W drops dramatically along the solid-liquid boundary. Therefore, the Gorecki criterion cannot be applied to describe the melting phenomenon of W. We also demonstrate that the vacancy-mediated melting model of Errandonea is inappropriate for explaining the emergence of abnormally low melting signals in diamond-anvil-cell measurements. Instead, the carbon contamination of W samples should be thoroughly considered to resolve the discrepancy between experimental and computational results. Finally, we revisit the vacancy correction technique of Hung et al. and find that it only depresses the melting temperature by a few percent. The listed pieces of evidence show that the influences of vacancies can be safely ignored when investigating the melting process of W under extreme conditions.

中文翻译：

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从非谐统计矩法对空位效应对 W 高压熔化的新见解


W 是一种无处不在的难熔金属，具有许多潜在应用，但其高压熔化行为仍然存在争议。一些物理学家建议，这个问题可以通过包括 vac 的贡献来解决。然而，由于缺乏有关恶劣环境中晶体学缺陷的信息，他们的想法仍未得到验证。在此，增强了统计矩方法，以阐明空位是如何形成并影响 W 的熔融特性的。我们的非谐波计算表明，众所周知的 Arrhenius 定律无法模拟等压加热过程中空位的扩散。此外，如果在等温压缩过程中忽略外部功的贡献，则空位形成的吉布斯能将被严重低估。在仔细研究了温度和压力效应之后，我们得出结论，W 的平衡空位浓度沿固液边界急剧下降。因此，Gorecki 准则不能用于描述 W 的熔化现象。我们还证明，Errandonea 的空位介导的熔化模型不适合解释金刚石-砧-电池测量中出现异常低的熔化信号。相反，应彻底考虑 W 样品的碳污染，以解决实验结果和计算结果之间的差异。最后，我们重新审视了 Hung 等人的空位校正技术，发现它只将熔化温度降低了几个百分点。列出的证据表明，在研究极端条件下 W 的熔化过程时，可以安全地忽略空位的影响。