Conversion of actinide nitrate surrogates into oxide using combustion synthesis process: A facile approach

In recent years, the focus of research in the conversion routes for the actinide nitrates into oxides for the generation IV nuclear fuel cycle have attracted rapidly growing interest. One process is the self-sustained exothermic reaction of Solution Combustion Synthesis (SCS) methodology. It was applied here to the reaction of an actinide surrogate Gd(NO₃)₃,6H₂O with glycine in air to produce ∼10⁻³ mol amounts of Gd₂O₃. The primary process parameters were the Gd/glycine ratio and heating rate, which affected the ignition temperature of the precursor mixture. An optimum ratio of one and a heating rate of 10 K min⁻¹ resulted in nearly complete SCS conversion over the 483–573 K temperature range and ultrafine gadolinia powders. The 100- to 500-fold swelling of the reactant mixture plays a dynamic role in the reactivity of the system. Final products were characterized by X-Rays Diffraction (XRD), surface area analysis, carbon content, and Scanning Electron Microscopy (SEM). The structural characteristics of the final gadolinia phases have been interpreted by the adiabatic flame temperature calculation.