Structures of oxyfluoroaluminates in molten cryolite-alumina mixtures investigated by DFT-based calculations

摘要

Aluminum is produced throughout the world using the H6roult-Hall process, which consists in the electrolysis of alumina [dissolved in cryolite melts, This dissolution of alumina gives rise to the formation of oxyfluoroaluminates, the structures of jwhicli vary with the composition of the electrolyte mixture. Up to now there has been no real consensus as to the structural Mtities of these fluoroaluminale ions. The lack of knowledge of the ionic species arising from the dissolution of alumina in (molten cryolite has led us to undertake structural, energetic and vibrational studies of these species using the methods of computational chemistry. Conformational and vibrational analyses of the ionic complexes were performed with the DGauss software on Cray G98 and C916 machines located at Cray Research, Eagan, MN, USA. A systematic study was carried out on the complexes [AlOF_X]~(1-x)(1