Investigation of the local structure of molten ThF4 – LiF and ThF4 – LiF – BeF2 mixtures by high-temperature X-ray absorption spectroscopy and molecular-dynamics simulation

The microscopic structures of ThF4 – LiF and ThF4 – LiF – BeF2 molten salts have been systematically investigated by in situ high-temperature X-ray absorption fine-structure (XAFS) spectroscopy combined with molecular-dynamics (MD) simulations. The results reveal that the local structure of thorium ions was much more disordered in the molten state of the ThF4 – LiF – BeF2 salt than that in ThF4 – LiF, implying that the Th and F ions were exchanged more frequently in the presence of Be ions. The structures of medium-range-ordered coordination shells (such as Th – F2nd and Th – Th) have been emphasized by experimental and theoretical XAFS analysis, and they play a significant role in transport properties. Using MD simulations, the bonding properties in the molten ThF4 – LiF and ThF4 – LiF – BeF2 mixtures were evaluated, confirming the above conclusion. This research is, to the best of our knowledge, the first systematic study on the ThF4 – LiF – BeF2 molten salt via quantitative in situ XAFS analysis and MD simulations.

Source: Journal of Synchrotron Radiation - August 19, 2019 Category: Physics Authors: Sun, J. Guo, X. Zhou, J. Dai, J. Song, S. Bao, H. Lin, J. Yu, H. He, S. Jiang, F. Long, D. Zhang, L. Wang, J.-Q. Tags: fluoride salts molecular dynamics simulations in situ XAFS medium-range-ordered structure transport properties research papers Source Type: research