Low-Dimensional Network Formation in Molten Sodium Carbonate

Area of Science:

• Materials Science
• Physical Chemistry
• Condensed Matter Physics

Background:

• Molten carbonates are highly inviscid liquids with low melting points.
• Their structure and properties, crucial for applications, remain poorly understood.
• Rare earth elements and volatile molecules exhibit high solubility in molten carbonates.

Purpose of the Study:

• To investigate the liquid structure of molten sodium carbonate (Na2CO3).
• To understand the temperature-dependent structural evolution and its impact on properties.

Main Methods:

• High-energy X-ray diffraction on laser-heated, containerlessly suspended carbonate spheres.
• Aerodynamic levitation furnace for sample manipulation in controlled atmospheres.
• Molecular dynamics simulations with flexible carbonate anions to determine partial structure factors.

Main Results:

• The liquid structure of molten sodium carbonate is strongly temperature-dependent.
• At lower temperatures (~1100 K), a low-dimensional carbonate chain network forms, with ~55% of carbon atoms in chains.
• Higher temperatures lead to shorter mean chain lengths and increased carbonate anion rotation.

Conclusions:

• The observed structural changes directly influence the dynamics of molten sodium carbonate.
• Increased temperature enhances the diffusion of sodium (Na+) ions due to reduced chain structures.
• This study provides fundamental insights into molten carbonate liquid dynamics and structure.