Ionic Species in Cryolite--Sodium Pyrophosphate Melts.

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

“…They proposed that the pyrophosphate anion dissociates in the melt and forms PO 4 3− , PO 3 − and PO 3 F 2− anions. Danek et al [4] and Chrenkova et al [5] carried out the analysis of freezing point depression in Na 3 AlF 6 -Al(PO 3 ) 3 , AlPO 4 and Na 3 PO 4 melts. In the case of Al(PO 3 ) 3 , dissociation of the metaphosphate anion (PO 3 − ) into orthophosphate anion (PO 4 3− ) and gaseous POF 3 was suggested.…”

“…Other components such as CaF 2 , MgF 2 , AlF 3 and LiF are also added to the electrolyte to derive the desired properties. Besides these compounds, the bath contains a wide range of impurities that enter the system with the raw materials (alumina, anodes).…”

“…Del Campo [2] and Bratland et al [3] have studied the phase diagram of the Na 3 AlF 6 -Na 4 P 2 O 7 binary system. They proposed that the pyrophosphate anion dissociates in the melt and forms PO 4 3− , PO 3 − and PO 3 F 2− anions.…”

Solubility of AlPO4 and NaVO3 in NaF−AlF3 Melts

“…Del Campo determined a phase diagram for the system Na 3 AlF 6 −Na 4 P 2 O 7 (CR = 3). Bratland et al on the basis of del Campo’s results considered reactions of the pyrophosphate anion (P 2 O 7 2− ) with the anions (AlF 6 3− , F − ) that form the PO 4 3− , PO 3 F 2− , and PO 3 − anions. The AlF 6 3− and F − anions are products of dissociation of molten cryolite.…”

“…1 Del Campo 4 determined a phase diagram for the system Na 3 AlF 6 -Na 4 P 2 O 7 (CR ) 3). Bratland et al 5 on the basis of del Campo's results considered reactions of the pyrophosphate anion (P 2 O 7 2-) with the anions (AlF 6 3-, F -) that form the PO 4…”