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

Abstract X-ray absorption fine structure (XAFS) measurements on rare-earth-alkali metal fluoride systems (0.2 LnF 3 –0.8 MF: Ln = La, Ce, Nd, Sm; M = Li, Na, K) have been carried out at 300 and 1173 K. The local structures around rare-earth-ions in both the solid and liquid phases were evaluated by the curve-fitting analysis, involving anharmonic oscillation effects at the higher temperature. This study revealed that the nearest-neighbour Ln 3+ –F − distance and the corresponding coordination number of F − around Ln 3+ in the molten state mainly depend on the lanthanide species rather than the size of the alkali metal ion.