Development of fuel-model interfaces: Characterization of Pd containing UO 2 thin films

• Published in: Journal of nuclear materials Vol. 397; no. 1; pp. 19 - 26
• Main Authors: Stumpf, S., Seibert, A., Gouder, T., Huber, F., Wiss, T., Römer, J., Denecke, M.A.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 2010
• ISSN: 0022-3115; 1873-4820
• DOI: 10.1016/j.jnucmat.2009.11.025

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.