Author:
Vinograd Victor L.,Bukaemskiy Andrey A.,Modolo Giuseppe,Deissmann Guido,Bosbach Dirk
Abstract
Available data on the dependence of the equilibrium chemical potential of oxygen on degrees of doping, z, and non-stoichiometry, x, y, in U1-zLnzO2+0.5(x-y) fluorite solid solutions and data on the dependence of the lattice parameter, a, on the same variables are combined within a unified structural-thermodynamic model. The thermodynamic model fits experimental isotherms of the oxygen potential under the assumptions of a non-ideal mixing of the endmembers, UO2, UO2.5, UO1.5, LnO1.5, and Ln0.5U0.5O2, and of a significant reduction in the configurational entropy arising from short-range ordering (SRO) within cation-anion distributions. The structural model further investigates the SRO in terms of constraints on admissible values of cation coordination numbers and, building on these constraints, fits the lattice parameter as a function of z, y, and x. Linking together the thermodynamic and structural models allows predicting the lattice parameter as a function of z, T and the oxygen partial pressure. The model elucidates contrasting structural and thermodynamic changes due to the doping with LaO1.5, on the one hand, and with NdO1.5 and GdO1.5, on the other hand. An increased oxidation resistance in the case of Gd and Nd is attributed to strain effects caused by the lattice contraction due to the doping and to an increased thermodynamic cost of a further contraction required by the oxidation.
Reference83 articles.
1. Decomposition of Uranium Dioxide at its Melting Point;Anderson;Nature,1960
2. Cooperativity Among Defect Sites in AO2+x and A4O9 (A=U, Np, Pu): Density Functional Calculations;Andersson;Phys. Rev. B,2009
3. Lattice Contraction and Lattice Deformation of UO2 and ThO2 Doped with Gd2 O3;Baena;J. Nucl. Mater.,2015
4. Radiation Induced Dissolution of (U,Gd)O2 Pellets in Aqueous Solution - A Comparison to Standard UO2 Pellets;Barreiro Fidalgo;J. Nucl. Mater.,2019
5. Solid Solutions in the System Urania-Rare-Earth Oxides: I, UO2-GdO1.5,;Beals;J. Am. Ceram. Soc.,1965
Cited by
6 articles.
订阅此论文施引文献
订阅此论文施引文献,注册后可以免费订阅5篇论文的施引文献,订阅后可以查看论文全部施引文献