Thermal Decomposition of Actinide Oxalates

The thermal decomposition of actinide oxalates, such as plutonium(III) and uranium(IV) oxalates, proceeds through sequential dehydration and ligand breakdown to yield stoichiometric dioxides. Initially, hydrated species lose crystalline water below about 150 °C, followed by stepwise cleavage of oxalate ligands between 200 °C and 400 °C, evolving CO₂ and forming transient oxalate–carbonate intermediates. Complete conversion to AnO₂ typically occurs above 400 °C, with the atmosphere influencing oxidation state and phase purity. Kinetic analyses by thermogravimetry and in situ X-ray diffraction report activation energies in the range of 250–450 kJ mol⁻¹, reflecting variations across the actinide series. Mechanistic studies highlight surface-diffusion and pore-migration as rate-controlling processes. The conventional thermal route remains the industry standard for preparing nuclear-grade oxide powders and sintered pellets, whereas emerging hydrothermal approaches at sub-critical water conditions enable the synthesis of nanocrystalline AnO₂ with high surface areas. Mastery of these transformations is vital for nuclear fuel fabrication, waste immobilisation and advanced materials design, underscoring their global significance.

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Thermal Decomposition of Actinide Oxalates publication trend

The graph below shows the total number of articles in thermal decomposition of actinide oxalates across all publications each year (not limited to Nature Index journals).

Technical terms

Thermal decomposition: Breakdown of a compound into simpler substances under heat.

Actinide oxalate: A coordination compound of an actinide metal with oxalate (C₂O₄²⁻) ligands.

Oxalate ligand: A bidentate ligand derived from oxalic acid that binds metal centres.

Activation energy: The minimum energy barrier that must be overcome for a chemical reaction to proceed.

Hydrothermal decomposition: Transformation of a precursor to an oxide under elevated temperature and pressure in aqueous media.

References

1. Grain growth of NpO 2 and UO 2 nanocrystals. RSC Advances (2023).
2. Synthesis of Nanocrystalline PuO2 by Hydrothermal and Thermal Decomposition of Pu(IV) Oxalate: A Comparative Study. Nanomaterials (2023).
3. Hydrothermal decomposition of actinide(IV) oxalates: a new aqueous route towards reactive actinide oxide nanocrystals. Open Chemistry (2016).
4. Probing the thermal decomposition of plutonium (III) oxalate with IR and Raman spectroscopy, X-ray diffraction, and electron microscopy. Journal of Nuclear Materials (2023).