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Simulation studies of transition metal and actinide oxides

Nicoll, Steven; (1995) Simulation studies of transition metal and actinide oxides. Doctoral thesis (Ph.D), UCL (University College London). Green open access

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Abstract

This thesis reports the results of several studies carried out using the technique of atomistic computer simulation. First, an investigation of the behaviour of several important fission products in UO2±x is discussed. With the aid of a simple statistical mechanical model of defect equilibria, the favoured location for single Xe atoms in UO2 is found to display a marked dependence on the Xe concentration. A predicted change in the preferred location of Xe as the Xe concentration is increased, is shown to coincide with a well known reduction in the diffusion coefficient of this fission product. Using similar techniques, the charge state and location of Mo atoms in UO2±x is then investigated. A computed estimate of the solubility of Mo in UO2±x is found to agree with the generally insoluble nature for this important fission product. Mo atoms dispersed in the lattice are calculated to have a charge state of no greater than 3+. Results are also given concerning the behaviour of atoms of the closely related fission products Ru, Rh and Pd. Finally, as a test of our model for fission product solubility, the behaviour of Sr and Ba in UO2 is investigated and the results compared with experiment. The clustering of defects in the highly non-stoichiometric transition metal oxides Mn1-xO, Fe1-xO, Co1-XO and Ni1-XO is a well studied phenomenon. In the final part of this thesis the effect of the dopants Mn, Fe, Co and Ni on the stability of several important defect structures in these oxides is investigated. If crystal field effects are included in the analysis, Fe is found to enhance the stability of {4:1} defect clusters in Mn1-XO, Co1-XO and Ni1-XO.

Type: Thesis (Doctoral)
Qualification: Ph.D
Title: Simulation studies of transition metal and actinide oxides
Open access status: An open access version is available from UCL Discovery
Language: English
Additional information: Thesis digitised by ProQuest.
Keywords: Pure sciences; Actinide oxides; Transition metal
URI: https://discovery.ucl.ac.uk/id/eprint/10103392
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