Understanding the Structure and Thermal Stability of Cs₃UCl₆(s) in the CsCl-UCl₃ System

Area of Science:

• Solid-state chemistry
• Inorganic chemistry
• Actinide science

Background:

• The CsCl-UCl₃ system is critical for thermochemical evaluations.
• Crystallographic data for Cs₃UCl₆(s) was previously unavailable.
• Accurate structural information is needed for molten salt applications.

Purpose of the Study:

• To synthesize and structurally characterize Cs₃UCl₆(s) for the first time.
• To provide essential crystallographic data for the CsCl-UCl₃ system.
• To investigate the thermal stability of Cs₃UCl₆(s).

Main Methods:

• Solid-state reaction for synthesis.
• Powder X-ray diffraction (XRD) with Rietveld refinement for structural analysis.
• ICP-MS for purity analysis and inert gas fusion for oxygen quantification.

Main Results:

• Cs₃UCl₆(s) was successfully synthesized and characterized.
• The compound crystallizes in a monoclinic unit cell (space group C2/c) with specific lattice parameters.
• High-temperature XRD revealed potential low-temperature polymorphic transformations.

Conclusions:

• The reported structural data resolves a deficiency in the understanding of the CsCl-UCl₃ system.
• This work provides a reliable reference for thermochemical assessments.
• The findings have implications for actinide science, especially in high-temperature molten salt systems.