Ab-initio simulation studies of chromium solvation in molten fluoride salts

Understanding molten salt chemistry is essential in ongoing research of the nuclear reactor (MSR). In this context, detailed understanding mechanisms underlying selective oxidation metal species, such as Cr, required to guide design effective corrosion mitigation strategies salts. An important starting point for mechanistic knowledge solvation structure and its role controlling speciation. work, we use ab initio molecular dynamics simulations study short-range (on scale nearest-neighbor bond lengths) medium-range (over length scales several neighbor spacings) three different fluoride melts with without Cr addition; namely, 2KF-NaF, 2LiF-BeF2, 3LiF-AlF3. We find that Cr0,Cr2+,Cr3+ can each be coordinated by numbers F-, variance coordination number decreasing state increases, these geometries are largely independent solvent. The manner which changes structure, however, found solvent-dependent. While 2KF-NaF show short medium range order highly dynamic, 2LiF-BeF2 3LiF-AlF3 characterized associates relatively long-lived organize into oligomer structures on larger scales. Rather than being solvated F- ions alone, incorporate within structure. Fluoroacidity, may therefore prove too simple a metric assessing corrosivity fluorides. As our work suggests, ability solvate must understood context short-