Atomic-Scale Insights into Interfacial Dynamics between LiF-BeF2-SmF3 Molten Salt and Solid Aluminum

Area of Science:

• Materials Science
• Physical Chemistry
• Computational Chemistry

Background:

• Molten LiF-BeF2 (FLiBe) salt is a key component in advanced nuclear reactors.
• Understanding the behavior of soluble fission products like SmF3 at interfaces is crucial for fuel reprocessing.
• Metallic aluminum (Al) interacts with FLiBe salt, influencing interfacial phenomena.

Purpose of the Study:

• To investigate the atomic-scale structure and dynamics at the FLiBe-Al interface.
• To elucidate the mechanism of samarium fluoride (SmF3) separation at this interface.
• To explore charge transfer and electrochemical transformations at the atomic level.

Main Methods:

• Ab initio molecular dynamics (AIMD) simulations were employed at 823 K.
• Analysis included charge density, charge transfer, coordination numbers, and ionic self-diffusion coefficients.
• Simulations focused on the FLiBe-Sm-Al system under an applied electric field.

Main Results:

• Electron transfer from Al to Sm occurs at the interface, leading to Sm valence reduction (Sm3+ to Sm2+).
• Significant charge transfer (1.04 ± 0.09 e) and interaction between Sm and Al were observed.
• Enhanced ionic diffusion near the interface, particularly perpendicular to the electric field, was identified.

Conclusions:

• The FLiBe-Al interface enables manipulation of charge and electrochemical transformations.
• Atomic-scale insights into interfacial chemistry provide links to macroscopic surface reactivity.
• This study offers fundamental understanding for SmF3 separation and molten salt reactor safety.