Temperature-Dependent Properties of Molten Li₂BeF₄ Salt Using Ab Initio Molecular Dynamics

Area of Science:

• Materials Science
• Nuclear Engineering
• Computational Chemistry

Background:

• Molten lithium tetrafluoroberyllate (FLiBe) is a key material for advanced nuclear reactors.
• Understanding its structural and property variations with temperature is crucial for reactor design.

Purpose of the Study:

• To investigate the temperature-dependent structure and properties of FLiBe from 0-2000 K.
• To analyze the electronic, optical, and mechanical properties of FLiBe in solid and liquid states.
• To correlate interatomic bonding with mechanical strength using total bond order density (TBOD).

Main Methods:

• High-throughput *ab initio* molecular dynamics simulations with a 504-atom supercell.
• Analysis of pair distribution function, coordination number, and bond angle distribution.
• Calculation of electronic structure, optical properties (refractive index), and mechanical properties.

Main Results:

• FLiBe exhibits anomalous behavior around its melting point (~732 K).
• Mechanical strength, band gap, and TBOD decrease non-linearly with increasing temperature.
• Refractive index shows a minimum at 850 K, above the melting point.

Conclusions:

• FLiBe's properties vary significantly between solid and liquid phases, with anomalous trends near melting.
• The study provides new insights into the temperature-dependent behavior of FLiBe for nuclear applications.
• First-time reporting of optical and mechanical properties, alongside a novel TBOD analysis.