| Autor: |
Semykina DO; Institute of Solid State Chemistry and Mechanochemistry SB RAS, 18 Kutateladze, 630128 Novosibirsk, Russia. kosova@solid.nsc.ru., Yakovlev IV; Boreskov Institute of Catalysis SB RAS, 5 Pr. Lavrent'eva, 630090 Novosibirsk, Russia., Lapina OB; Boreskov Institute of Catalysis SB RAS, 5 Pr. Lavrent'eva, 630090 Novosibirsk, Russia., Kabanov AA; Samara State Technical University, SCTMS, 12 Novo-Sadovaya, 443110 Samara, Russia and P. N. Lebedev Physical Institute of the Russian Academy of Sciences, 221 Novo-Sadovaya, 443011 Samara, Russia., Kosova NV; Institute of Solid State Chemistry and Mechanochemistry SB RAS, 18 Kutateladze, 630128 Novosibirsk, Russia. kosova@solid.nsc.ru. |
| Abstrakt: |
A sample with a nominal composition 'NaVPO4F' is prepared by mechanochemically assisted solid-state synthesis using quenching. A detailed study of its crystal and local structure is conducted by means of XRD and FTIR and solid-state 31P NMR spectroscopies in comparison with Na3V2(PO4)2F3. It is shown that the as-prepared 'NaVPO4F' has a multiphase composition, including NaVPO4F as the main phase and Na3V2(PO4)2F3 and Na2.57V4P4O17F as the side products. The crystal structure of NaVPO4F is described in the monoclinic C2/c space group. It is characterized by negligible V3+/V4+ oxidation with the corresponding F-/O2- substitution and the presence of structural disordering. Using the Voronoi-Dirichlet partition (VDP) method, the Na+ and Li+ migration pathways in Tavorite-like NaVPO4F and closely related LiVPO4F (with the triclinic structure, P1[combining macron] S.G.) are analyzed. While the Na+ migration is suppressed in both cases, the Na+/Li+ ion exchange in NaVPO4F with the formation of monoclinic LiVPO4F could occur, but is difficult due to the sodium immobility rather than the instability of the lithium derivatives as was concluded from the DFT calculations. |
