| Article ID | Journal | Published Year | Pages | File Type |
|---|---|---|---|---|
| 1313704 | Journal of Fluorine Chemistry | 2012 | 6 Pages |
Different techniques are used to understand the Na3AlF6–FeF3 system behavior. Rietveld's structure refinement analysis is successfully applied to determine the lattice parameters as well as relative phase abundance of individual phases in the system Na3AlF6–FeF3. The results confirm the presence of Na3(AlxFey)F6 and Na5(AlxFey)3F14 (x + y = 1) solid solutions, depending on the amount of FeF3 in the system. The system with 25 mol% FeF3 contains crystalline phases in weight ratio: 64.8 ± 2.8% of Na3(AlxFey)F6 and 35.2 ± 2.7% of Na5(AlxFey)3F14, respectively. In the first mentioned solution, the molar ratio of Al/Fe is 92.8/7.2 and 77.4/22.6 in second one. Weight loss measurements suggest that some new volatile products are emitted from the melt. MAS NMR investigations of the condensate exclude the presence of iron containing fluorides in the condensed sample and confirm that NaAlF4 is the only vapor species, generating in the melted system.
Graphical abstractThe Rietveld's structure refinement analysis was successfully applied for the determination of the lattice parameters as well as relative phase abundance of individual phases in the system Na3AlF6–FeF3. The results show that FeF3 impurity dissolves in the cryolite melt in the form of Na3(AlxFey)F6 and Na5(AlxFey)3F14 (x + y = 1) solid solutions, depending to the various amount of FeF3 in the melt. The MAS NMR investigation excluded the presence of iron containing fluorides in condensed sample and confirms NaAlF4 like reaction product, evaporated from the melt.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► FeF3 dissolves in the Na3AlF6 melt in the form of various solid solutions. ► System with 25 mol% FeF3 contains crystalline phases in weight ratio: 64.8 ± 2.8% of Na3(AlxFey)F6 and 35.2 ± 2.7% of Na5(AlxFey)3F14, respectively. ► Non-ferrous unique volatile product originates in the system Na3AlF6–FeF3. ► It confirms Fe3+/Al3+ substitution but not the traditional view of forming FeF63− species in AlF63− melts.
