Vibrational modes and structure of rare earth halide–alkali halide binary melts YBr3–ABr (A=Li, K, Cs) and YF3–KF

Local Structure Analogy of Lanthanide Fluoride Molten Salts

“…The deviation from linearity observed in the LnF 3 -LiF systems indicates the existence of more than two kinds of fluorine environments. This observation is in agreement with the work of Papatheodorou and his co-workers [13,14] using Raman spectroscopy. They have shown that the LnF 3 -AlkF melts (Alk = alkalin) should consist of LnX 3− 6 octahedral species, more or less connected, depending on the LnF 3 content in the melt.…”

“…They are indeed highly corrosive and volatile, and the melting temperatures are high (700-1800 K). Most of the previous work deals with the electrochemical [8,9] and thermodynamic properties [10,11] and very few spectroscopic studies [12][13][14][15] have been done. The latter are important to provide coordination numbers and interatomic distances and are helpful for electrochemical experiment analysis and for building potentials in numerical simulations.…”

In situ high temperature NMR and EXAFS experiments in rare-earth fluoride molten salts

“…Two explanations can be put forward: the local structure is continuously and monotonously changed with the melt composition, or at least another complex arises as the composition becomes richer in YF 3 . At the same time, 7 Li chemical shift remains the same whatever the composition, thus supporting the second hypothesis. Unfortunately, the chemical shift range of 7 Li is very weak and this result does not allow us to definitely conclude.…”

“…As regards structure of the molten lanthanide fluorides, nature of neighbours, coordination and distances around the cation, is still matter of debate. So far, the main spectroscopic results have been carried out by Raman spectroscopy [7]. For instance, in molten KF-LnF 3 binary systems rich in KF, the lanthanides appear to be in an octahedral configuration LnF 6 3-for all the lanthanide systems studied.…”

Evidence of dynamical local scale distribution heterogeneities in CsF-AF (A=Li, Na, K and Rb) molten salts

“…39,64,65,66 The proportion of these environments depends on the concentration of MF x . For example, this number of fluorine n ranges mainly between 6 and 8 for rare earth.…”