XAFS analysis of molten rare-earth-alkali metal fluoride systems

High temperature NMR approach of mixtures of rare earth and alkali fluorides: An insight into the local structure

“…The 19 F MAS spectrum of LaF 3 at room temperature exhibits the three components at À25.2, 12.4 and 19.7 ppm (Figs. 1 and 2) corresponding to the three fluorine sites of the structure, in good agreement with the work of Wang and Grey [27] who studied the mobility of fluorine sites in connection with ionic conductivity.…”

“…In binaries, a medium range order generated by bridging fluorines between octahedra has been described for composition rich in LnX 3 . Only very few informations are known for fluorides mainly by Raman, NMR and EXAFS spectroscopy [8,[16][17][18][19]. The work of G. Papatheodorou's group by Raman spectroscopy, have shown that the predominant species in molten AlkF-LnF 3 mixtures are the LnF 6 3À octahedra.…”

“…The 19 F chemical shifts sign the structural evolution from the anion point of view, and because of its great sensitivity to the local environment of the fluorine atoms it is possible to describe the network connectivity in solids, or to discriminate the bridging or non-bridging fluorines. There are several studies about 19 F chemical shifts calculation in inorganic solids [22][23][24][25][26]. From the analysis of a large number of 19 F isotropic chemical shifts measured in inorganic solids, with different F-sites, Bureau et al [26] propose some empirical correlation confirmed by ab initio calculations, relating chemical shifts to structural parameters.…”

“…There are several studies about 19 F chemical shifts calculation in inorganic solids [22][23][24][25][26]. From the analysis of a large number of 19 F isotropic chemical shifts measured in inorganic solids, with different F-sites, Bureau et al [26] propose some empirical correlation confirmed by ab initio calculations, relating chemical shifts to structural parameters. They showed that fluorines can be classified into three categories: shared and unshared fluorines between two octahedra, and free fluorines which are not implied in these MF 6 octahedra.…”

Transport in molten LiF–NaF–ZrF4 mixtures: A combined computational and experimental approach

“…In molten fluorides, Raman [2] as well as classical NMR or EXAFS [3][4][5][6][7][8][9] studies have recently been undertaken by several groups, and proved to be efficient in determining the cationic environments in a wide range of melt compositions. On the contrary, matter transport is difficult to quantify with precision.…”