Application of internal gelation to sol-gel synthesis of ceria-doped zirconia microspheres as nuclear fuel analogous materials

Optimizing of internal gelation based on the sol-gel synthesis was carried out for manufacturing of plutonium-doped zirconia microspheres used as nuclear fuels. In the present study, cerium was used as a surrogate for plutonium. So far, the Er_0.05Y_0.1Ce_xZr_0.85-xO _1.925 (x = 0.0-0.2) microspheres were successfully sintered to suppress the rapid reaction such as the thermal decomposition of by-products such as ammonium nitrate and formaldehyde at the calcination process. However, some cracks and pores were still observed in the sintered microspheres. As a result, these sintered densities reached 71-86% TD. From the crystallographic point of view, the sintered zirconia microspheres had the cubic fluorite structure and well formed the solid-solution oxide. The lattice constant of cubic zirconia increased with the amount of doped ceria.