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oai:www.ideals.illinois.edu:2142/45289 2023-07-11 col_2142_5131 col_2142_14837 com_2142_5130 com_2142_14836 com_2142_234

http://hdl.handle.net/2142/45289 en Copyright 2013 Joseph R. Bernhardt  Radiation-enhanced diffusion (RED) UO2 Anion Diffusion Uranium dioxide thin films Radiation-enhanced diffusion of oxygen-18 in uranium dioxide thin films text Heuser, Brent J. Bernhardt, Joseph 2013-08-22T16:34:53Z 2013-08-22T16:34:53Z 2013-08 2013-08-22T16:34:53Z 2013-08 Anion radiation enhanced diffusion (RED) and thermal diffusion of a buried 18O tracer layer in thin film UO2 was measured using Secondary-Ion Mass Spectroscopy (SIMS). Thin films were grown using a dedicated magnetron sputtering chamber. Samples were irradiated with 1.8 MeV Kr+ over a temperature range from 295 K to 623 K. Measurements have been made for both single crystal and textured films. This difference in crystal structure led to significantly different results. Thin film stoichiometry was also shown to have an effect on RED and thermal diffusion. For RED, activation energies found from best fit analysis were Ea = 0.83 and Ea = 0.37, for single crystal and textured samples, respectively. RED for single crystal UO2 thin films can be represented by, D_RED=8.7×〖10〗^(-14) exp⁡((-0.83)/kT) 〖cm〗^2/sec RED for textured UO2 thin films can be represented by, D_RED=2.0×〖10〗^(-15) exp⁡((-0.37)/kT) 〖cm〗^2/sec Thermal diffusion measurements resulted, from best fit analysis, in similar activation energies for single crystal and textured thin films, Ea = 0.46 and Ea = 0.53, respectively. This was shown to agree well with published experimental and calculated values for UO2-x for anion vacancies. Thin films used in this work were thought to be substoichiometric and thermal diffusion is thought to be controlled by anion vacancies. Mixing parameter measurements found ξ = 2.1 ± 0.2〖 Å〗^5 〖eV〗^(-1) on the anion sublattice, which indicated that ballistic mixing was the dominant mechanism of ion-mixing and that thermal spike activity is negligible. Item withdrawn by Mark Zulauf (zulauf@illinois.edu) on 2013-07-06T17:06:55Z Item was in collections: University of Illinois Theses & Dissertations (ID: 1) No. of bitstreams: 2 Bernhardt_Joseph.docx: 2644416 bytes, checksum: 233924c95bf71865e2adea29335d5b29 (MD5) Bernhardt_Joseph.pdf: 1895851 bytes, checksum: e3e93702e070e0e701f1ad0bd815a58a (MD5) Made available in DSpace on 2013-08-22T16:34:53Z (GMT). No. of bitstreams: 4 Joseph_Bernhardt.pdf: 1896131 bytes, checksum: c3c0fde8f730a2ed693f34a6443342ed (MD5) Bernhardt_Joseph.docx: 2644525 bytes, checksum: 60021bd34b679f046d9a4116dd514ab7 (MD5) 1_Bernhardt_Joseph.docx: 2644525 bytes, checksum: 60021bd34b679f046d9a4116dd514ab7 (MD5) license.txt: 4066 bytes, checksum: 9b4fce084ad3959ad7c7a6eb3a86fd39 (MD5) 5183 Nuclear, Plasma, & Rad Engr 1973 Nuclear, Plasma, Radiolgc Engr University of Illinois at Urbana-Champaign Thesis M.S. MS: Nucl, Plasma, Rad Eng-UIUC 10KS5183MS