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First-Principles Determination of Transference Numbers in Cryolitic Melts
Industrial & Engineering Chemistry Research ( IF 3.8 ) Pub Date : 2020-06-26 , DOI: 10.1021/acs.iecr.0c02281
Aïmen E. Gheribi 1 , Mathieu Salanne 2 , Didier Zanghi 3 , Kelly Machado 3 , Catherine Bessada 3 , Patrice Chartrand 1
Affiliation  

The charge and electron-transport properties of molten ionic systems are among the most relevant properties to consider in the control of several electrochemical processes. First-principles-based equilibrium molecular dynamics (EMD) can provide reliable predictions of both total and partial charge-transport properties. In this work, we calculate the charge-transport properties of the electrolytic bath (Na3AlF6–AlF3–Al2O3) of the Hall–Héroult electrolysis cells. We predict both individual and collective charge-transport properties (total and partial conductivities and self-diffusion coefficients) for 11 different compositions typical of industrial conditions via a series of EMD simulations. The predicted total and partial ionic conductivities and their composition dependence are compared to available experimental data. A good agreement is obtained for all studied compositions. From a more fundamental point of view, the microscopic aspect of the charge-transport properties of cryolitic melts is discussed through its correlation with the local structure of different melts. Deviations between the calculated partial conductivities and those derived via the Nernst–Einstein approximation can be explained by the presence of strong short-range ordering within the melts.

中文翻译:

低温熔体中迁移数的第一性原理确定

熔融离子系统的电荷和电子传输性质是控制几种电化学过程时要考虑的最相关的性质。基于第一原理的平衡分子动力学(EMD)可以提供全部和部分电荷传输性质的可靠预测。在这项工作中,我们计算了电解槽(Na 3 AlF 6 –AlF 3 –Al 2 O 3)的霍尔–埃洛特电解槽。通过一系列EMD模拟,我们预测了11种不同工业条件下典型组成的个体和集体电荷传输性质(总和部分电导率以及自扩散系数)。将预测的总离子电导率和部分离子电导率及其组成依赖性与可用的实验数据进行比较。对于所有研究的组合物均获得良好的一致性。从更基本的角度出发,通过与冰晶质熔体的局部结构相关性,对冰晶质熔体的电荷传输性质的微观方面进行了讨论。熔体内存在强短程有序现象,可以解释计算出的部分电导率与通过Nernst-Einstein近似推导的部分电导率之间的偏差。
更新日期:2020-07-22
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