Structure-property relationships in actinide containing molten salts – A review: Understanding and modelling the chemistry of nuclear fuel salts

Development of Deep Potentials of Molten MgCl2–NaCl and MgCl2–KCl Salts Driven by Machine Learning

“…Besides, the discrepancies of peak height for Mg–Cl in molten MK are obvious, which hints the larger variation of transport properties for molten MK as responses to temperature. From Figure a, the average E bar of Mg–Cl of 3.32 for molten MK is greater than that of 2.43 for molten MN, verifying the strong stability of Mg–Cl in molten MK and giving a reason to the low N of Mg–Cl pair in molten MK . Additionally, the E bar of Mg–Cl is three times larger than those of Na–Cl (1.12) and K–Cl (0.99), indicating that Mg–Cl makes the main contributions to energy fluctuations, related to the thermodynamic characteristics of a system.…”

“…The platforms of Mg–Cl are obvious in both systems and the R cut is marked in Figure to specify the corresponding N , where the 5- and 4-coordination structures are dominant for molten MN and MK, respectively. In addition, the average coordination number of Na–Cl ( N = 6) is lower than that of K–Cl ( N = 7), related to its small ratio of cation/anion ionic radius, meaning that more bridging network structures can be formed in molten MK . As compared to the experimental N of cation–Cl for pure MgCl 2 ( N = 4.3), NaCl ( N = 5.8), and KCl ( N = 6.1), the N s of Mg–Cl, Na–Cl, and K–Cl for molten MN and MK become higher, indicating that the abilities of these cations to snatch Cl are improved in molten mixtures.…”

“…It can be seen that the distances of Na–Na, K–K, and Mg–Mg are less than twice of Na–Cl, K–Cl, and Mg–Cl distances, suggesting the existence of twisted Na/K/Mg–Cl–Na/K/Mg linkages. Besides, the distortion degree of K–Cl–K or Cl–K–Cl is significantly larger than the other cations, indicating more generally of the formation of connected K chains, which works in concert with short-range to intermediate-range ordered structures in molten MK.…”

“…From Figure 6a, the average E bar of Mg−Cl of 3.32 for molten MK is greater than that of 2.43 for molten MN, verifying the strong stability of Mg−Cl in molten MK and giving a reason to the low N of Mg−Cl pair in molten MK. 49 Additionally, the E bar of Mg−Cl is three times larger than those of Na−Cl (1.12) and K−Cl (0.99), indicating that Mg−Cl makes the main contributions to energy fluctuations, related to the thermodynamic characteristics of a system. Furthermore, the similar E bar for Na−Cl and K−Cl in Figure 6b suggests that Cl − needs the same energy to be away from Na + and K + , and the consistent stability of Na−Cl and K−Cl bonds also corresponds to peak heights of their RDFs.…”

“…8,9,17 As shown in Figure 5 and Table S2, the first peak position varies little with temperature, which means the intermolecular distance is insensitive to temperature. 14 connected K chains, 49 which works in concert with short-range to intermediate-range ordered structures in molten MK.…”