Multi-nuclear magnetic resonance study of Na3AlF6-AlPO4 molten and solidified mixtures

M. Keppert , A. Rakhmatullin (1, 2) , F. Simko , M. Deschamps (1, 2) , G.M. Haarberg , C. Bessada (1, 2)

1 CEMHTI - Conditions Extrêmes et Matériaux : Haute Température et Irradiation
2 FRMN-SHC - Fédération RMN du Solide à Hauts Champs

Phosphorus is one of the predominant impurities in the Hall-Heroult process for industrial aluminium production. The nature of the dissolved phosphorus species in the Na3AlF6AlPO4 system has been investigated by in situ high-temperature (HT) 19F, 23Na, 27Al, 17O, and 31P NMR. The combination of these experiments enables to define the presence of PO43-, AlF52- and (AlF4OPO3)4- anions in the melt, and then the formation of AlOP bonding. Melts solidified at different cooling rates were characterised using various solid-state NMR techniques including multiple quantum magic angle spinning (MQMAS), rotational echo double resonance (REDOR) and heteronuclear single quantum correlation (HSQC). The glass obtained by the rapid quenching of the hypereutectic melt has been carefully described in order to better understand the structure of the melt.

Domaines: Matériaux

M. Keppert, A. Rakhmatullin, F. Simko, M. Deschamps, G.M. Haarberg, et al.. Multi-nuclear magnetic resonance study of Na3AlF6-AlPO4 molten and solidified mixtures. Magnetic Resonance in Chemistry, 2008, 46, pp.803-810. ⟨10.1002/mrc.2248⟩. ⟨hal-00332524⟩