Thermochemical modeling of the U1−yGdyO2±x phase

McMurray, Jake W.; Shin, Dongwon; Slone, B.W.; Besmann, Theodore M.

doi:10.1016/j.jnucmat.2013.08.005

Cited by 15 publications

(5 citation statements)

References 21 publications

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“…The population variance ( 2 ) estimates stochastic variations due to impurity effects, sample preparation and sample degradation. Numerous compounds are able to form a solid solution with UO2, thus influencing the lattice parameter of the unit cell [27,28,[40][41][42][43][44][45]. Experimental data, however, is not yet available for every system.…”

Section: 3lattice Parameter Analysismentioning

confidence: 99%

Accurate lattice parameter measurements of stoichiometric uranium dioxide

Leinders¹,

Cardinaels²,

Binnemans³

et al. 2015

Journal of Nuclear Materials

108

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The paper presents and discusses lattice parameter analyses of pure, stoichiometric UO2. Attention was paid to prepare stoichiometric samples and to maintain stoichiometry throughout the analyses. The lattice parameter of UO2.000 ± 0.001 was evaluated as being 547.127 ± 0.008 pm at 20 °C, which is substantially higher than many published values for the UO2 lattice constant and has an improved precision by about one order of magnitude. The higher value of the lattice constant is mainly attributed to the avoidance of hyperstoichiometry in the present study and to a minor extent to the use of the currently accepted CuK X-ray wavelength value. Many of the early studies used CuK wavelength values that differ from the currently accepted value, which also contributed to an underestimation of the true lattice parameter.

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Section: 3lattice Parameter Analysismentioning

confidence: 99%

Accurate lattice parameter measurements of stoichiometric uranium dioxide

Leinders¹,

Cardinaels²,

Binnemans³

et al. 2015

Journal of Nuclear Materials

108

View full text Add to dashboard Cite

show abstract

“…These experiments invariably show that the larger the doping, the higher is the chemical potential, or, equivalently, the partial pressure of oxygen, at which a given degree of nonstoichiometry can be attained. Studies based on point-defect theory (Park and Olander, 1992), CALPHAD methodology (Saunders and Miodownik, 1998;Hillert, 2001) and on dual solution Gibbs energy minimization method (Karpov et al, 2001;Kulik et al, 2013) provided thermodynamically sound models able to predict the equilibrium partial pressure of oxygen at a given degree of doping and/or non-stoichiometry (Guéneau et al, 2011;McMurray et al, 2013;Degueldre et al, 2014;McMurray et al, 2015;Lee et al, 2016a;McMurray and Silva, 2016;Curti and Kulik, 2020). However, little effort has been so far invested in correlating these models with lattice parameter data.…”

Section: Introductionmentioning

confidence: 99%

Thermodynamic and Structural Modelling of Non-Stoichiometric Ln-Doped UO2 Solid Solutions,Ln = {La, Pr, Nd, Gd}

et al. 2021

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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.

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“…In the databases on oxide fuels from Canada and the Netherlands, there are mainly stoichiometric compounds [14,15,16,17,18] and a few solutions are described for the fluorite oxide phase, in which the dissolution of numerous dissolved fission and activation products is described, and the noble metal phases [16]. In the United States, extended models were developed to describe mixed oxides (U,Ln)O2±x and related phase diagrams with Ln=Pr, La, Nd, Y, Gd, Ce [19,20,21,22,23,24,25,26]. In these databases, not all the solutions (solid and liquid) are modeled for all the systems.…”

Section: Taf-id Projectmentioning

confidence: 99%