Existence of Al2F7-in molten MF-AlF3 (M =K, Cs) systems as determined by Raman spectroscopy and structural simulation

• 来源期刊: 能源化学
• 年，卷（期）: 2020,（5）
• 页码范围: 19-23
• 页数: 5页
• 语种: 英文

摘要

The molten mixtures of alkali metal fluorides and aluminum fluoride are applied as aluminum electrolytes or brazing fluxes.However,the presence of Al2F7-in such molten systems is disputed.In the present study,MF-AlF3 (M =K,Cs) systems with molar ratios ＜ 1 were studied by in-situ Raman spectroscopy and molecular simulation.The results show that,in addition to AlF63-,AlF52-,and AlF4-,the systems also contained Al2F7-.The characteristic bands in the Raman spectra belonging to Al2F7-were located at about 225 cm-1,315 cm-1,479 cm-1,and 720 cm-1.There are two possible structures of Al2F7-,which belong to the D3d and D3h point groups.Both of these structures are linear,and their single-point energies were found to differ by only 0.31 kcal/mol.