Aluminium phosphate behaviour in Na₃AlF₆–Al₂O₃ melts: a new insight from in situ high temperature NMR measurements

Abstract

The formation of complex oxofluoroaluminate species containing bridging oxygen atoms from the chemical processes between AlPO4, Al2O3, and Na3AlF6.

Structural correlations and chemistry of the Na3AlF6 − SiO2 melt as an electrolyte for the solar grade silicon (SOG − Si) electrowinning

“…It means, that the increase of the SiO 2 content in the melt is related to the formation of four-coordinated aluminum Al(O,F) 4 . A dissolution of alumina (Al 2 O 3 ) and phosphate (AlPO 4 ) in cryolite melts was being previously studied by high temperature NMR and by MD simulations with DFT calculations [32,34,35] , was latter predicted by thermodynamic modeling in the molten systems containing Na, O, Si, and F atoms [41]. The presence of fluorine−containing alkali silicate glasses with Si−O−F tetrahedral is also reported in the following systems; MF−SiO 2 (M=alkali metals) and AlF 3 −SiO 2 [42−43].…”