Development of fuel-model interfaces: Characterization of Pd containing UO2 thin films

Abstract The presented work aims to reproducibly prepare UO 2 –Pd thin film model systems for spent nuclear fuel in order to further investigate surface reactions of these films under relevant redox conditions. The sputter co-deposition of U and Pd in the presence of O 2 results in the homogeneous distribution of Pd in a crystalline UO 2 matrix. Hereby, Pd is found to be oxidized and to form PdO x . Heating the films after deposition causes the diffusion of film components and induces a change in surface morphology. Independent of the heating temperature initial UO 2+ x transforms into UO 2 . This is different for the noble metal. At high temperatures (550–840 °C) Pd diffuses into the Si-wafer substrate and forms mixed Pd–Si–U alloys. At moderate temperatures (150–200 °C) Pd solely diffuses within the film matrix and forms micrometer sized metallic particles. These particles are further characterized as being an agglomeration of small nanometer sized spheres.