Electrochemical effects of isolated voids in uranium dioxide |
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| Institution: | 1. School of Nuclear Engineering, Purdue University, West Lafayette, Indiana 47906, USA;2. Department of Materials Science and Engineering, University of Florida, Gainesville, Florida 32611, USA;1. Key Laboratory of Cryogenics, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190, P.R. China;2. Graduate University of Chinese Academy of Sciences, Beijing 100049, P.R. China;3. Department of Physics, Zunyi Normal College, Zunyi 563002, P.R. China;1. Ruđer Bošković Institute, Division of Materials Physics, Bijenička cesta 54, P.O. Box 180, HR-10002 Zagreb, Croatia;2. Jožef Stefan Institute, Department for Nanostructured Materials, Jamova cesta 39, SI-1000 Ljubljana, Slovenia;3. University of Zagreb, Faculty of Science, Department of Physics, Bijenička cesta 32, P.O. Box 331, HR-10002, Zagreb, Croatia;4. University of Zagreb, Faculty of Chemical Engineering and Technology, Marulićev trg 19, HR-10000 Zagreb, Croatia;1. Department of Physics, National Institute of Technology, Hamirpur Himachal Pradesh, 177005, India;2. National Physical Laboratory, New Delhi 110012, India;3. Centre for Material Science and Engineering, National Institute of Technology, Hamirpur, Himachal Pradesh 177005, India;1. College of Ero-environment & Urban-construction, Fujian University of Technology, Fuzhou 350108, China;2. College of Material Science and Engineering, Fuzhou University, Fuzhou 350108, China;3. Department of Physics and Electronic, Minjiang University, Fuzhou 350108, China;4. Institute of Polymer Optoelectronic Materials and Devices, South China University of Technology, Guangzhou 510641, China;5. Fujian Key Laboratory of Microelectronics & Integrated Circuits, Fuzhou 350108, China;1. Technical Physics Division, Bhabha Atomic Research Centre, Mumbai-400085, India;2. Atomic & Molecular Physics Division, Bhabha Atomic Research Centre, Mumbai-400085, India |
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| Abstract: | We present a model to study the electrochemical effects of voids in oxide materials under equilibrium conditions and apply this model to uranium dioxide. Based on thermodynamic arguments, we claim that voids in uranium dioxide must contain oxygen gas at a pressure that we determine via a Kelvin equation in terms of temperature, void radius and the oxygen pressure of the outside gas reservoir in equilibrium with the oxide. The oxygen gas within a void gives rise to ionosorption and the formation of a layer of surface-charge on the void surface, which, in turn, induces an influence zone of space charge into the matrix surrounding the void. Since the space charge is carried in part by atomic defects, it is concluded that, as a part of the thermodynamic equilibrium of oxides containing voids, the off-stoichiometry around the void is different from its remote bulk value. As such, in a uranium dioxide solid with a void ensemble, the average off-stoichiometry level in the material differs from that of the void-free counterpart. The model is applied to isolated voids in off-stoichiometric uranium dioxide for a wide range of temperature and disorder state of the oxide. |
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| Keywords: | A Oxides D Defects D Electrochemical properties D Microstructure |
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