Structural investigations of (La,Pu)PO4 monazite solid solutions: XRD and XAFS study

Arinicheva, Yulia; Popa, Karin; Scheinost, Andreas C.; Roßberg, André; Blanco, Oliver Dieste; Raison, Philippe E.; Cambriani, Andrea; Somers, J.; Bosbach, Dirk; Neumeier, Stefan

doi:10.1016/j.jnucmat.2017.06.034

Cited by 26 publications

(19 citation statements)

References 64 publications

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“…[11] Both mineralso ften contain appreciable quantities of Ua nd Th in nature, but remain stable over geological timescales despitet he constant radiation exposure from the decay of theser adionuclides. [10,12] Such high structural durability and radiation resistance lead to the suggestion of xenotimeand monazite-type ceramics as potential hosts for the immobilization of long-lived high-level radioactivew aste. [13] In this regard, basic understanding of the resulting solid solutions, such as their structuralc hemistry and thermodynamic stabilities are important prerequisites for assessing their viability as a nuclear waste form.…”

Section: Introductionmentioning

confidence: 99%

Local Structural Effects of Eu³⁺ Incorporation into Xenotime‐type Solid Solutions with Different Host Cations

Xiao

Lösch

Huittinen

et al. 2018

Chemistry A European J

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In this study, the effect of host cations on the local structure around the dopant site of materials from the xenotime family is systematically studied on the molecular level. A series of six Eu -doped xenotime-type single crystals (Tb, Y, Ho, Er, Yb, and LuPO ) have been grown and spectroscopically analyzed by using polarization-dependent laser-induced luminescence spectroscopy (p-TRLFS). Our results demonstrate that the structural disorder changes in a non-linear manner with a structural break between Yb and Lu . Despite adopting identical crystal structures, the solid solutions of these materials vary significantly, and differ from monazite solid solutions. Similar Eu incorporation behavior with a strongly distorted dopant site is found for the early members of the xenotime family, whereas LuPO with the largest host versus dopant radii mismatch is anomalous in that it contains the most symmetrical lattice site. This goes along with a significantly stronger crystal field, indicating a shorter Eu-O bond length, as well as a strong vibronic coupling to external translational lattice vibrations. The p-TRLFS analysis confirms the breakdown of the crystallographic site symmetry from D to C in YPO , whereas a small distortion of the crystallographic site in LuPO results in an S point symmetry for the Eu cation. The lattice with the smallest cation host site is no longer sufficiently flexible to make room for Eu and instead "forces" the guest ion to occupy a less distorted Lu site.

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Section: Introductionmentioning

confidence: 99%

Local Structural Effects of Eu³⁺ Incorporation into Xenotime‐type Solid Solutions with Different Host Cations

Xiao

Lösch

Huittinen

et al. 2018

Chemistry A European J

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“…Formation and thermodynamic stability of solid solutions of radionuclides-bearing lanthanide phosphates ceramic waste forms is a topic of extensive studies in the context of nuclear waste management (Popa et al, 2007a; Li et al, 2014; Kowalski and Li, 2016; Arinicheva et al, 2017; Hirsch et al, 2017; Neumeier et al, 2017b; Eremin et al, 2019). This is because the information gained allows for the assessment of long term stability of ceramic nuclear waste forms against phase separation.…”

Section: Resultsmentioning

confidence: 99%

Rare-Earth Orthophosphates From Atomistic Simulations

Kowalski

Kegler

et al. 2019

Front. Chem.

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Lanthanide phosphates ( LnPO 4 ) are considered as a potential nuclear waste form for immobilization of Pu and minor actinides (Np, Am, and Cm). In that respect, in the recent years we have applied advanced atomistic simulation methods to investigate various properties of these materials on the atomic scale. In particular, we computed several structural, thermochemical, thermodynamic and radiation damage related parameters. From a theoretical point of view, these materials turn out to be excellent systems for testing quantum mechanics-based computational methods for strongly correlated electronic systems. On the other hand, by conducting joint atomistic modeling and experimental research, we have been able to obtain enhanced understanding of the properties of lanthanide phosphates. Here we discuss joint initiatives directed at understanding the thermodynamically driven long-term performance of these materials, including long-term stability of solid solutions with actinides and studies of structural incorporation of f elements into these materials. In particular, we discuss the maximum load of Pu into the lanthanide-phosphate monazites. We also address the importance of our results for applications of lanthanide-phosphates beyond nuclear waste applications, in particular the monazite-xenotime systems in geothermometry. For this we have derived a state-of-the-art model of monazite-xenotime solubilities. Last but not least, we discuss the advantage of usage of atomistic simulations and the modern computational facilities for understanding of behavior of nuclear waste-related materials.

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“…Actinide-bearing solid solutions with monazite structure were successfully prepared by the solid state synthesis route. Popa et al [71], and Arinicheva et al [72] as well as Zhang and Vance [73] reported the preparation of single phase La 1−x Pu x PO 4 solid solutions up to a Pu-content of 15 mol%. The oxidation state +III of Pu was confirmed by XANES [68,72] and diffuse reflectance spectroscopy [73], respectively.…”

Section: Lnpo 4 Phosphates: Monazite and Xenotimementioning

confidence: 99%

“…Popa et al [71], and Arinicheva et al [72] as well as Zhang and Vance [73] reported the preparation of single phase La 1−x Pu x PO 4 solid solutions up to a Pu-content of 15 mol%. The oxidation state +III of Pu was confirmed by XANES [68,72] and diffuse reflectance spectroscopy [73], respectively. For self-irradiation studies, (La,Pu)PO 4 doped with 238 Pu was synthesised by a wet chemical method based on precipitation from aqueous nitrate solutions by Burakov et al [19,58].…”

Section: Lnpo 4 Phosphates: Monazite and Xenotimementioning

confidence: 99%

New insights into phosphate based materials for the immobilisation of actinides

Neumeier

Arinicheva

et al. 2017

Radiochimica Acta

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This paper focuses on major phosphate-based ceramic materials relevant for the immobilisation of Pu, minor actinides, fission and activation products. Key points addressed include the recent progress regarding synthesis methods, the formation of solid solutions by structural incorporation of actinides or their non-radioactive surrogates and waste form fabrication by advanced sintering techniques. Particular attention is paid to the properties that govern the long-term stability of the waste forms under conditions relevant to geological disposal. The paper highlights the benefits gained from synergies of state-of-the-art experimental approaches and advanced atomistic modeling tools for addressing properties and stability of f-element-bearing phosphate materials. In conclusion, this article provides a perspective on the recent advancements in the understanding of phosphate based ceramics and their properties with respect to their application as nuclear waste forms.

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Structural investigations of (La,Pu)PO4 monazite solid solutions: XRD and XAFS study

Cited by 26 publications

References 64 publications

Local Structural Effects of Eu³⁺ Incorporation into Xenotime‐type Solid Solutions with Different Host Cations

Local Structural Effects of Eu³⁺ Incorporation into Xenotime‐type Solid Solutions with Different Host Cations

Rare-Earth Orthophosphates From Atomistic Simulations

New insights into phosphate based materials for the immobilisation of actinides

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Structural investigations of (La,Pu)PO4 monazite solid solutions: XRD and XAFS study

Cited by 26 publications

References 64 publications

Local Structural Effects of Eu3+ Incorporation into Xenotime‐type Solid Solutions with Different Host Cations

Local Structural Effects of Eu3+ Incorporation into Xenotime‐type Solid Solutions with Different Host Cations

Rare-Earth Orthophosphates From Atomistic Simulations

New insights into phosphate based materials for the immobilisation of actinides

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Product

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Local Structural Effects of Eu³⁺ Incorporation into Xenotime‐type Solid Solutions with Different Host Cations

Local Structural Effects of Eu³⁺ Incorporation into Xenotime‐type Solid Solutions with Different Host Cations