Spark Plasma Sintering of fine-grained SrWO4 and NaNd(WO4)2 tungstates ceramics with the scheelite structure for nuclear waste immobilization

Потанина, Е. А.; Орлова, А. И.; Михайлов, Д. А.; Нохрин, А. В.; Чувильдеев, В. Н.; Болдин, М. С.; Сахаров, Н. В.; Lantcev, E A; Tokarev, M.G.; Мурашов, А. А.

doi:10.1016/j.jallcom.2018.09.348

Cited by 34 publications

(21 citation statements)

References 54 publications

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“…For the SrWO 4 phase, W is coordinated with four O atoms to form WO 4 tetrahedra. 29 PLE and PL spectra of SWO:xMn 4+ (x = 0.001, 0.003, 0.005, 0.008, and 0.01) phosphors at room temperature are shown in Figure S2. The PLE spectrum monitored at 695 nm (1.78 eV) possesses two broad bands ranging from 270 (4.59 eV) to 560 nm (2.21 eV), which can be fitted by four Gaussian components.…”

Section: Resultsmentioning

confidence: 99%

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Tuning Coordination Environments of Dopants through Topochemical Reaction Enables Substantial Enhancement of Luminescence in Mn⁴⁺-Doped Perovskite

et al. 2021

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Synthesizing highly luminescent active iondoped phosphors is desirable for many related applications but, remains challenging when a conventional solid-state reaction method is used for this purpose. In this contribution, we demonstrate the transformation of a poorly luminescent phase with a photoluminescence quantum yield (PLQY) of 3.1% to highly luminescent cousins with a PLQY of 58.9%, through a post-synthetically topochemical reaction treatment, as illustrated in a Mn4+-doped Sr3WO6 model system. Detailed structural analyses, combined with spectroscopic results, revealed that the highly luminescent treated samples have larger W–O distances, and the volume of the [(W/Mn)O6] octahedron in the structure was expanded with respect to the precursor, as a result of the formation of oxygen vacancies. We find that topochemical reduction causes the conversion of W6+ ions to W5+, while it does not impact the oxidation state of Mn4+ ions. These changes lead to the release of the chemical pressure around the Mn4+ ions, resulting in significant suppression of non-radiative recombination and thus greatly enhanced luminescence. We believe that our concept proposed here has the potential to be extended to tuning the properties of other functional materials that are sensitive to the local crystal environments of dopants.

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Section: Resultsmentioning

confidence: 99%

“…In light of the similar ion radius and valence, the Mn 4+ ions (CN = 6, r = 0.54 Å) are expected to situate at the W 6+ sites (CN = 6, r = 0.62 Å) in Sr 3 WO 6 . For the SrWO 4 phase, W is coordinated with four O atoms to form WO 4 tetrahedra …”

Section: Resultsmentioning

confidence: 99%

Tuning Coordination Environments of Dopants through Topochemical Reaction Enables Substantial Enhancement of Luminescence in Mn⁴⁺-Doped Perovskite

et al. 2021

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“…30. Scheelite [89,440,441,442,443,444,445,446,447,448,449,450,451,452,453,454,455,456,457], Figure 30.…”

Section: Crystalline Ceramic Phasementioning

confidence: 99%

“…Many of the compounds listed here have been studied and continue to be actively investigated by researchers led by the co-author of this work (Prof Orlova), including those with structures of garnet [185,189,190,191,192,193,194], P-pollucite [205,206,207,208,209,210,211,212,213,214,215], pollucite [214,215,293], monazite [141,352], sodium zirconium phosphate (NZP) [21,209,383,384,388,392,393,394,396,405,407,408,409,412,413,414,415,416,417,418,419], langbeinite [416,417,418,419], whitlockite [87,89,424,425,426,427,428,429,430] and scheelite [89,445,446]. Overall crystalline ceramics are characterized as much more durable compared with glasses of the same chemical compo...…”

Section: Summary Of Crystalline Ceramic Waste-formsmentioning

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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“…The study of such compounds is very important for the immobilization of actinide elements (which constitute a special group of long-term ecologically hazardous radionuclides) in order to isolate these ones from the biosphere for the long time required for the storage and disposal. For this purpose, the world's leading laboratories are currently studying ceramic materials based on natural minerals [1]: monazite [2,3], garnet [3][4][5][6][7][8][9][10][11][12][13][14][15][16][17], kosnarite [18][19][20][21], pyrochlore [10,[22][23][24][25], scheelite [26], etc. The garnet structure is one of the most promising matrices for the MA immobilization.…”

Section: Introductionmentioning

confidence: 99%

Study of the Hydrolytic Stability of Fine-Grained Ceramics Based on Y2.5Nd0.5Al5O12 Oxide with a Garnet Structure under Hydrothermal Conditions

et al. 2021

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The hydrolytic stability of ceramics based on Y2.5Nd0.5Al5O12 oxide with a garnet structure obtained by the spark plasma sintering (SPS) method has been studied. The tests were carried out in distilled water under hydrothermal conditions in an autoclave and, for comparison, in a static mode at room temperature. The mechanism of leaching of Y and Nd from the ceramics was investigated. It has been shown that at “low” temperatures (25 and 100 °C), the destruction of pores occured, and the intensity of the leaching process was limited by the diffusion of ions from the inner part of the sample to the surface. At “high” test temperatures (200 and 300 °C), intense destruction of the ceramic grain boundaries was observed. It was assumed that the accelerated leaching of neodymium is due to the formation of grain-boundary segregations of Nd3+ in sintered ceramics.

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Spark Plasma Sintering of fine-grained SrWO4 and NaNd(WO4)2 tungstates ceramics with the scheelite structure for nuclear waste immobilization

Cited by 34 publications

References 54 publications

Tuning Coordination Environments of Dopants through Topochemical Reaction Enables Substantial Enhancement of Luminescence in Mn⁴⁺-Doped Perovskite

Tuning Coordination Environments of Dopants through Topochemical Reaction Enables Substantial Enhancement of Luminescence in Mn⁴⁺-Doped Perovskite

Ceramic Mineral Waste-Forms for Nuclear Waste Immobilization

Study of the Hydrolytic Stability of Fine-Grained Ceramics Based on Y2.5Nd0.5Al5O12 Oxide with a Garnet Structure under Hydrothermal Conditions

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Spark Plasma Sintering of fine-grained SrWO4 and NaNd(WO4)2 tungstates ceramics with the scheelite structure for nuclear waste immobilization

Cited by 34 publications

References 54 publications

Tuning Coordination Environments of Dopants through Topochemical Reaction Enables Substantial Enhancement of Luminescence in Mn4+-Doped Perovskite

Tuning Coordination Environments of Dopants through Topochemical Reaction Enables Substantial Enhancement of Luminescence in Mn4+-Doped Perovskite

Ceramic Mineral Waste-Forms for Nuclear Waste Immobilization

Study of the Hydrolytic Stability of Fine-Grained Ceramics Based on Y2.5Nd0.5Al5O12 Oxide with a Garnet Structure under Hydrothermal Conditions

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Tuning Coordination Environments of Dopants through Topochemical Reaction Enables Substantial Enhancement of Luminescence in Mn⁴⁺-Doped Perovskite

Tuning Coordination Environments of Dopants through Topochemical Reaction Enables Substantial Enhancement of Luminescence in Mn⁴⁺-Doped Perovskite