Studies on magnetic properties of UO2CeO2 solid solutions

Hinatsu, Yukio; Fujino, Takeo

doi:10.1016/0022-4596(88)90119-3

Cited by 20 publications

(15 citation statements)

References 29 publications

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“…This result is not inconsistent with the conclusions drawn from room-temperature XANES measurements for (U 0.33 Ce 0.67 )O 2 mixtures 12 , where an immeasurable concentration of Ce 3+ was reported. From detailed measurements of Néel temperatures, low-temperature magnetic susceptibilities, and electron paramagnetic resonance (EPR), Hinatsu and Fujino concluded that charge transfer occurs to non-zero, albeit limited, extent in urania-ceria solid solutions even at the low temperatures where their measurements were conducted [9][10][11] . A detailed analysis of the magnetic properties of urania-ceria mixtures within the current model of charge transfer is beyond the scope of the current work.…”

Section: Summary and Discussionmentioning

confidence: 99%

“…The thermophysical properties of urania-ceria mixtures have been investigated for more than three decades [1][2][3][4][5][6][7][8][9][10][11][12][13] , due to the relevance of these materials to the understanding of nuclear fuel behavior. Cerium is a fission product that is highly soluble in urania (UO 2 ) 1 , and its effects on phase stability, thermal conductivity and ionic diffusion are thus relevant to the performance of oxide fuels, particularly at high burnup.…”

Section: Introductionmentioning

confidence: 99%

“…In addition to the extensive studies of phase equilibria, a variety of thermophysical properties have been measured for urania-ceria mixtures. These properties include oxygen partial molar free energies and enthalpies 4 , lattice parameters 5 , bond lengths 6 , heat capacities 7,8 , magnetic properties [9][10][11] , and electronic structure 12,13 . While many of the properties of urania-ceria are relatively well characterized, there are at present no published values of the mixing thermodynamic properties (enthalpy, entropy and free energy) that the authors are aware of.…”

Section: Introductionmentioning

confidence: 99%

“…As reviewed in Refs. 9,12 , it was first reported nearly a century ago that Ce-rich urania-ceria solid solutions form a deep blue color that stands in sharp contrast to the yellow and brown colors of pure CeO 2 and UO 2 , respectively. As reviewed by Griffiths et al, this deep blue color has been proposed to arise from charge transfer between U and Ce cations, forming a solid solution composed of mixed charge states 14 .…”

Section: Introductionmentioning

confidence: 99%

“…1. In a series of papers reporting measurements of magnetic properties for a range of cerium compositions, Hinatsu and Fujino concluded that solid solutions with low cerium fraction exhibited some formation of Ce 3+ and U 5+ , while those of higher cerium fraction (>0.50) even form Ce 3+ and U(VI) [9][10][11] . In contrast to these conclusions, X-ray absorption near edge structure (XANES) measurements performed by Antonio et al for a (U 0.33 Ce 0.67 )O 2 solid solution were reported to show no evidence for the presence of Ce 3+ or U 5+ ions.…”

Section: Introductionmentioning

confidence: 99%

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Computational study of the energetics of charge and cation mixing in U1−xCexO2
Hanken
¹
,
Stanek
²
,
Grønbech‐Jensen
³

et al. 2011
Phys. Rev. B
37
0
25
1
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The formalism of electronic density-functional-theory, with Hubbard-U corrections (DFT+U), is employed in a computational study of the energetics of fluorite-structured U1−xCexO2 mixtures. The computational approach makes use of a procedure which facilitates convergence of the calculations to multiple self-consistent DFT+U solutions for a given cation arrangement, corresponding to different charge states for the U and Ce ions in several prototypical cation arrangements. Results indicate a significant dependence of the structural and energetic properties on the nature of both charge and cation ordering. With the effective Hubbard-U parameters that reproduce well the measured oxidation-reduction energies for urania and ceria, we find that charge transfer between U 4+ and Ce 4+ ions, leading to the formation of U 5+ and Ce 3+ , gives rise to an increase in the mixing energy in the range of 4-14 kJ/mol of formula unit, depending on the nature of the cation ordering. The results suggest that although charge transfer between uranium and cerium ions is disfavored energetically, it is likely to be entropically stabilized at the high temperatures relevant to the processing and service of urania-based solid solutions.

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Section: Summary and Discussionmentioning

confidence: 99%