Mechanical behaviour near grain boundaries of He-implanted UO2 ceramic polycrystals

Ibrahim, Mohamed S.; Castelier, Étienne; Palancher, H.; Bornert, Michel; Caré, Sabine; Micha, Jean‐Sébastien

doi:10.1016/j.jnucmat.2016.10.044

Cited by 2 publications

(2 citation statements)

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“…In the context of radioactive waste management, the large expansion in volume and mechanical stress resulting from the corrosion of spent nuclear fuel (SNF) during storage [36][37][38][39][40] is one of the main hazards that must be avoided in the disposal of high level radioactive nuclear waste (HLRNW) [41]. The large increase in volume of SNF may result in the increase of the pressure suffered by the components of the barrier system used in a deep geological disposal of HLRNW and can lead to certain problems in the containment of the waste.…”

Section: Introductionmentioning

confidence: 99%

Revealing Rutherfordine Mineral as an Auxetic Material

Colmenero

2018

Applied Sciences

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The mechanical behavior of the uranyl carbonate mineral, rutherfordine, UO2CO3, was studied by means of theoretical solid-state methods based in Density Functional Theory using plane waves and pseudopotentials. The results of the computations reported in this work show that this mineral exhibits the important negative Poisson ratio (NPR) phenomenon. In order to show that this feature is not an artifact associated to the theoretical treatment employed, additional calculations were carried out using very large calculation parameters. These calculations improved the mechanical description of this mineral and confirmed its auxeticity, i.e., it shows NPR values. Rutherfordine is a highly anisotropic material showing a maximum value of the NPR of the order of −0.3 ± 0.1 for applied stresses directed along the X axis, the transverse direction being the Y axis perpendicular to the structural sheets in rutherfordine structure. The underlying reason for this observation is that under the effect of applied positive pressures, the interlayer space between the sheets of rutherfordine vary in the opposite way to the expected behavior; that is, it decreases instead of increasing.

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Section: Introductionmentioning

confidence: 99%

Revealing Rutherfordine Mineral as an Auxetic Material

Colmenero

2018

Applied Sciences

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“…This is surprising since the underlying atomistic deformation modes and interactions determine thermodynamic phase stability and transformation. Except the theoretical studies of Weck et al [68,69] on the uranyl peroxide hydrates, studtite and metastudtite, and the studies of the mechanical behavior of uranium dioxide [70][71][72], no experimental or computational studies have reported the mechanical properties of these phases. Furthermore, the Born conditions of mechanical stability of the corresponding structures have not been analyzed.…”

Section: +mentioning

confidence: 99%

Theoretical Studies of the Structural, Mechanical and Raman Spectroscopic Properties of Uranyl-Containing Minerals

Ruiz¹

2019

Minerals

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The incipient use of theoretical methods in the research of geomaterials reveals the great power of such methodology in the determination of the mineral properties. These methods provide a safe, accurate and cheap manner of obtaining these properties. Uranium-containing minerals are highly radiotoxic, and their experimental studies demand a careful handling of the samples used. However, theoretical methods are free of such inconveniences and may be used in the complete characterization of this type of minerals. Theoretical methods are not only a complement to the use of other experimental techniques but also a powerful predictive tool. The structural, mechanical and Raman spectroscopic properties of uranyl-containing materials, including rutherfordine soddyite, schoepite and uranophane-α, were studied by means of theoretical solid-state methods based on density functional theory using plane waves and pseudopotentials. A new norm-conserving relativistic pseudopotential for uranium atom developed in recent works was employed. These minerals are among the most important secondary phases arising from corrosion of spent nuclear fuel under the final geological disposal conditions. The computed crystal structures of these materials as well as the corresponding and X-ray powder patterns were found to be in excellent agreement with the experimental information. Therefore, the optimized structures of these minerals were employed to study the mechanical properties and stability of these minerals. These properties were obtained using the finite deformation technique. All these minerals were found to be mechanically stable since the corresponding Born stability conditions were satisfied. A large amount of relevant mechanical data were reported including bulk, Young and Shear moduli, Poisson ratios, ductility and hardness indices, anisotropy measures as well as longitudinal and transversal wave velocities. The large volume expansion and mechanical stress resulting from the corrosion of spent nuclear fuel during storage emphasize the great relevance of the mechanical information of the waste components. Finally, the computation of vibrational properties of these minerals is studied. The computed Raman spectra of these materials were found to be in good agreement with their experimental

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Mechanical behaviour near grain boundaries of He-implanted UO2 ceramic polycrystals

Cited by 2 publications

References 20 publications

Revealing Rutherfordine Mineral as an Auxetic Material

Revealing Rutherfordine Mineral as an Auxetic Material

Theoretical Studies of the Structural, Mechanical and Raman Spectroscopic Properties of Uranyl-Containing Minerals

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