Micro-structure studies of the molten binary K3AlF6–Al2O3 system by in situ high temperature Raman spectroscopy and theoretical simulation,Inorganic Chemistry Frontiers

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Micro-structure studies of the molten binary K3AlF6–Al2O3 system by in situ high temperature Raman spectroscopy and theoretical simulation
Inorganic Chemistry Frontiers ( IF 6.1 ) Pub Date : 2018-06-07 00:00:00 , DOI: 10.1039/c8qi00226f
Nan Ma _{1,

2,

3,

4,

5} , Jinglin You _{1,

2,

3,

4,

5} , Liming Lu _{6,

7,

8,

9} , Jian Wang _{1,

2,

3,

4,

5} , Min Wang _{1,

2,

3,

4,

5} , Songming Wan _{5,

10,

11,

12,

13}

Affiliation

In order to assist in predicting the properties of molten cryolite-alumina electrolytes widely used in the Hall–Héroult process, the micro-structure of the molten binary system was investigated by in situ high temperature Raman spectroscopy from room temperature to 1273 K under an argon atmosphere. The symmetric stretching vibrational wavenumbers of possible clusters in the molten system were further calculated through quantum chemistry ab initio simulations and compared with the experimental Raman spectra of the molten system. The molten K₃AlF₆–Al₂O₃ system was found to consist of [AlF₅]²⁻, [AlF₆]³⁻, [Al₂OF₆]²⁻ and [Al₂O₂F₄]²⁻ clusters. With the increasing addition of Al₂O₃ to molten K₃AlF₆, the structure of six-coordinated Al atoms connected by terminal fluorine is partly believed to evolve into a structure of two four-coordinated Al atoms connected by single-bridging oxygen. The mole percentage of the species in the melt was also calculated from the experimental Raman spectra. As the Al₂O₃ content increased from 0 to 8.0 wt%, the content of [Al₂OF₆]²⁻ in the melt was found to increase swiftly from 0 to 33.0 mol%, while the [Al₂O₂F₄]²⁻ content decreased after reaching a maximum of 1.5 mol%.

中文翻译：

原位高温拉曼光谱研究熔融二元K ₃ AlF ₆ -Al ₂ O ₃体系的微观结构及理论模拟

为了帮助预测在Hall–Héroult过程中广泛使用的熔融冰晶石-氧化铝电解质的性能，通过在氩气下从室温到1273 K的原位高温拉曼光谱研究了熔融二元体系的微观结构。气氛。通过量子化学从头算，进一步计算了熔融体系中可能团簇的对称拉伸振动波数，并将其与熔融体系的实验拉曼光谱进行了比较。发现熔融的K ₃ AlF ₆ -Al ₂ O ₃系统由[AlF ₅ ] ²⁻，[AlF ₆ ]组成。^3-，[Al₂ OF₆ ]^2-和[Al₂ O₂ F₄ ]^2-簇。随着向熔融的K₃ AlF_6中增加Al₂ O_3的添加，部分地认为通过末端氟连接的六配位Al原子的结构演变为通过单桥氧连接的两个四配位Al原子的结构。熔体中物质的摩尔百分比也由实验拉曼光谱计算得出。随着Al₂ O_3的含量从0增加到8.0 wt％，[Al₂ OF的含量_[6 ]发现熔体中的^2-从0迅速增加到33.0mol％，而[Al₂ O₂ F₄ ]^2-的含量在达到最大1.5mol％之后降低。

更新日期：2018-06-07

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