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 tem...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 K_(3)AlF_(6)-Al_(2)O_(3)system was found to consist of[AlF_(5)]^(2-),[AlF_(6)]^(3-),[Al_(2)OF_(6)]^(2-)and[Al_(2)O_(2)F_(4)]^(2-)clusters.With the increasing addition of Al_(2)O_(3)to molten K_(3)AlF_(6),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 Al_(2)O_(3)content increased from 0 to 8.0 wt%,the content of[Al_(2)OF_(6)]^(2-)in the melt was found to increase swiftly from 0 to 33.0 mol%,while the[Al_(2)O_(2)F_(4)]^(2-)content decreased after reaching a maximum of 1.5 mol%.展开更多
基金financial support from the National Natural Science Foundation of China(grant numbers 50932005 and 21773152)Shanghai Committee of Science and Technology Fund,China(grant number 12520709200)+3 种基金Open Project Program of the State Key Laboratory of Advanced Special Steel,Shanghai University,China(grant number SKLASS2015-01,SKLASS2017-02)Independent Research and Development Project of State Key Laboratory of Advanced Special Steel,Shanghai University(SKLASS 2016-Z01)Program of Introducing Talents of Discipline to Universities(Supported by 111 Project)Special Fund Project of Shanghai Municipality for Science and Technology Development(YDZX20173100001316).
文摘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 K_(3)AlF_(6)-Al_(2)O_(3)system was found to consist of[AlF_(5)]^(2-),[AlF_(6)]^(3-),[Al_(2)OF_(6)]^(2-)and[Al_(2)O_(2)F_(4)]^(2-)clusters.With the increasing addition of Al_(2)O_(3)to molten K_(3)AlF_(6),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 Al_(2)O_(3)content increased from 0 to 8.0 wt%,the content of[Al_(2)OF_(6)]^(2-)in the melt was found to increase swiftly from 0 to 33.0 mol%,while the[Al_(2)O_(2)F_(4)]^(2-)content decreased after reaching a maximum of 1.5 mol%.
