Chemical durability and leaching mechanism of Ce0.5Eu0.5PO4 ceramics: Effects of temperature and pH values

Zhao, Xiaofeng; Teng, Yan; Wu, Lei; Huang, Yi; Ma, Jiyan; Wang, Guolong

doi:10.1016/j.jnucmat.2015.08.012

Cited by 19 publications

(10 citation statements)

References 45 publications

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“…Obviously, the low concentration of Nd 3+ in rhabdophane lattice is more likely to form a coordination structure with a higher relative intensity at Nd-3d 5/2 state. Compared with the Nd-3d 3/2 orbitals, the electron concentration in Nd-3d 5/2 orbital has lower binding energy with an energy difference of approximate 23 29 :…”

Section: Raman Analysismentioning

confidence: 99%

“…Monazite (LnPO 4 , Ln = La‐Gd) is an important light lanthanide phosphate mineral for U and Th bearing, and has been considered as a potential ceramic matrix for the immobilization of actinides (An) waste streams because of its outstanding characteristics of chemical stability, irradiation stability, and mechanical stability 19–21 . The long‐term chemical stability of monazite benefits from the protection of rhabdophane (LnPO 4 ⋅0.667H 2 O) precipitation on the surface of the specimen 22,23 . It is generally believed that the leaching actinides from monazite matrix will be adsorbed immediately by the defective area of monazite surface to the nucleation of Ln x An 1‐ x PO 4 ·0.667H 2 O rhabdophane precipitation 16,24,25 .…”

Section: Introductionmentioning

confidence: 99%

“…[19][20][21] The long-term chemical stability of monazite benefits from the protection of rhabdophane (LnPO 4 ⋅0.667H 2 O) precipitation on the surface of the specimen. 22,23 It is generally believed that the leaching actinides from monazite matrix will be adsorbed immediately by the defective area of monazite surface to the nucleation of Ln x An 1-x PO 4 ⋅0.667H 2 O rhabdophane precipitation. 16,24,25 Recently, Gausse et al reported that the standard solubility products (log Ksp) of LnPO 4 ⋅0.667H 2 O rhabdophane in 0.1 mol/L HCl solutions at 298-343 K are approximate 25, implying the feasibility of separation-enrichment of actinides from rhabdophane in acidic solutions.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Investigation of Nd³⁺incorporation in Ce‐rhabdophane: Insight from structural flexibility and occupation mechanism

et al. 2022

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LnPO4·0.667H2O rhabdophane has been considered as a potential material for the precipitation of actinides from radioactive waste liquid, owing to its outstanding characteristics of high actinide bearing and easy synthesis in acid solutions. However, a comprehensive understanding of the actinide occupation and the precipitation response of rhabdophane to remove actinides has yet to be established. In this study, the effect of ions concentration and pH values on the detailed precipitation reaction of CexNd1‐xPO4·0.667H2O rhabdophane in acid solutions are systematically investigated. Some specific issues such as structural distortion and flexibility, and occupation mechanism are discussed by combining with experiments and density functional theory (DFT) calculation. The results reveal that ions concentration and pH values have a significant impact on the crystallization nucleation step before 12 h. The obtained removal rate of Nd3+ is more than 99% in pH 1–5 solutions with the ions concentration of 0.05–0.1 mol/L. Moreover, incorporating Nd in CePO4·0.667H2O rhabdophane will easily result in the lattice distortion in b‐axis. DFT calculation and X‐ray photoelectron spectroscopy (XPS) results reveal that Nd is preferentially incorporated in nonhydrated site to form a weaker binding energy of NdO8 polyhedron.

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Section: Raman Analysismentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Investigation of Nd³⁺incorporation in Ce‐rhabdophane: Insight from structural flexibility and occupation mechanism

et al. 2022

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“…23. Monazite [12,16,17,18,87,89,140,141,231,235,244,293,331,332,333,334,335,336,337,338,339,340,341,342,343,344,345,346,347,348,349,350,351,352,353,354,355,356,357,358,359], Figure 23.…”

Section: Crystalline Ceramic Phasementioning

confidence: 99%

Ceramic Mineral Waste-Forms for Nuclear Waste Immobilization

2019

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Crystalline ceramics are intensively investigated as effective materials in various nuclear energy applications, such as inert matrix and accident tolerant fuels and nuclear waste immobilization. This paper presents an analysis of the current status of work in this field of material sciences. We have considered inorganic materials characterized by different structures, including simple oxides with fluorite structure, complex oxides (pyrochlore, murataite, zirconolite, perovskite, hollandite, garnet, crichtonite, freudenbergite, and P-pollucite), simple silicates (zircon/thorite/coffinite, titanite (sphen), britholite), framework silicates (zeolite, pollucite, nepheline /leucite, sodalite, cancrinite, micas structures), phosphates (monazite, xenotime, apatite, kosnarite (NZP), langbeinite, thorium phosphate diphosphate, struvite, meta-ankoleite), and aluminates with a magnetoplumbite structure. These materials can contain in their composition various cations in different combinations and ratios: Li–Cs, Tl, Ag, Be–Ba, Pb, Mn, Co, Ni, Cu, Cd, B, Al, Fe, Ga, Sc, Cr, V, Sb, Nb, Ta, La, Ce, rare-earth elements (REEs), Si, Ti, Zr, Hf, Sn, Bi, Nb, Th, U, Np, Pu, Am and Cm. They can be prepared in the form of powders, including nano-powders, as well as in form of monolith (bulk) ceramics. To produce ceramics, cold pressing and sintering (frittage), hot pressing, hot isostatic pressing and spark plasma sintering (SPS) can be used. The SPS method is now considered as one of most promising in applications with actual radioactive substances, enabling a densification of up to 98–99.9% to be achieved in a few minutes. Characteristics of the structures obtained (e.g., syngony, unit cell parameters, drawings) are described based upon an analysis of 462 publications.

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“…Sintering at higher temperature was observed to result in the decomposition of the phosphate group [147]. Hot-pressing methods allow for lowering the sintering temperature by about 250-300°C at 30 MPa, yielding pellets with 98 % relative density [143,[148][149][150][151][152]. Du et al [153][154][155] achieved the same density (98 %) of La-monazite after 3 min of sintering at 1350°C (heating rate 100°C · min −1 ) at a pressure of 40 MPa using Spark Plasma Sintering (SPS).…”

Section: Densification Of Phosphate Ceramicsmentioning

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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Chemical durability and leaching mechanism of Ce0.5Eu0.5PO4 ceramics: Effects of temperature and pH values

Cited by 19 publications

References 45 publications

Investigation of Nd³⁺incorporation in Ce‐rhabdophane: Insight from structural flexibility and occupation mechanism

Investigation of Nd³⁺incorporation in Ce‐rhabdophane: Insight from structural flexibility and occupation mechanism

Ceramic Mineral Waste-Forms for Nuclear Waste Immobilization

New insights into phosphate based materials for the immobilisation of actinides

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Chemical durability and leaching mechanism of Ce0.5Eu0.5PO4 ceramics: Effects of temperature and pH values

Cited by 19 publications

References 45 publications

Investigation of Nd3+incorporation in Ce‐rhabdophane: Insight from structural flexibility and occupation mechanism

Investigation of Nd3+incorporation in Ce‐rhabdophane: Insight from structural flexibility and occupation mechanism

Ceramic Mineral Waste-Forms for Nuclear Waste Immobilization

New insights into phosphate based materials for the immobilisation of actinides

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Investigation of Nd³⁺incorporation in Ce‐rhabdophane: Insight from structural flexibility and occupation mechanism

Investigation of Nd³⁺incorporation in Ce‐rhabdophane: Insight from structural flexibility and occupation mechanism