Niobium- and bismuth-silver phosphate glasses for the conditioning of radioactive iodine

Chabauty, Anne Lise; Campayo, Lionel; Méar, F.O.; Montagne, Lionel

doi:10.1016/j.jnoncrysol.2019.01.015

Cited by 17 publications

(14 citation statements)

References 29 publications

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“…Although 129 I is not a strong thermo‐active radioisotope (β‐γ emitter), the recent advances in the development of specific incorporation matrix, such as Ag‐based phosphate 71 and tellurite, 72 is not an entirely suitable solution considering the low T g of these materials (<200°C).…”

Section: Discussionmentioning

confidence: 99%

The influence of iodide on glass transition temperature of high‐pressure nuclear waste glasses

et al. 2020

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The glass transition temperature (T g) is a key parameter to investigate for application in nuclear waste immobilization in borosilicate glasses. T g for several glasses containing iodine (I) has been measured in order to determine the I effect on T g. Two series of glass composition (ISG and NH) containing up to 2.5 mol% I and synthesized under high pressure (0.5 to 1.5 GPa) have been investigated using differential scanning calorimetry (DSC). The I local environment in glasses has been determined using X-ray photoelectron spectroscopy and revealed that I is dissolved under its iodide form (I −). Results show that T g is decreased with the I addition in the glass in agreement with previous results. We also observed that this T g decrease is a strong function of glass composition. For NH, 2.5 mol% I induces a decrease of 24°C in T g , whereas for ISG, 1.2 mol% decreases the T g by 64°C. We interpret this difference as the result of the I dissolution mechanism and its effect on the polymerization of the boron network. The I dissolution in ISG is accompanied by a depolymerization of the boron network, whereas it is the opposite in NH. Although ISG corresponds to a standardized glass, for the particular case of I immobilization it appears less adequate than NH considering that the decrease in T g for NH is small in comparison to ISG.

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Section: Discussionmentioning

confidence: 99%

The influence of iodide on glass transition temperature of high‐pressure nuclear waste glasses

et al. 2020

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“…The XAS (both X-ray Absorption Near-Edge Structure, XANES; and Extended X-ray Absorption Fine Structure, EXAFS) is of particular interest as it probes the local environment for a given element. It has been successfully applied for the investigation of I local environment in various materials at both the K-and L-edges: crystalline [4,[21][22][23]; organic [24][25][26]; solution [27] and glass [9][10][11]14,[28][29][30].…”

Section: Introductionmentioning

confidence: 99%

Iodine local environment in high pressure borosilicate glasses: An X-ray photoelectron spectroscopy and X-ray absorption spectroscopy investigation

Morizet

Jolivet

Trcera

et al. 2021

Journal of Nuclear Materials

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The 129 I radioactive isotope is a by-product of nuclear plants activity. Owing to its strong volatility, there is currently no ideal protocol to immobilize 129 I in nuclear waste borosilicate glasses. Recently, we have proposed the use of high-pressure syntheses to dissolve iodine in various glass compositions; however, I speciation and dissolution mechanism could not be determined.We have adopted an approach combining X-ray Photoelectron Spectroscopy (XPS) and X-ray Absorption Spectroscopy (XAS) methods to determine I speciation and molecular environment in glasses containing from 0.5 to 2.5 mol.% I. The XPS spectra reveal that I is mostly dissolved as iodide (>85% I -) with a small proportion of elemental iodine (<15% I 0 ) and the absence of iodate species (I 5+ ). For borosilicate glasses, the XAS results and subsequent spectrum simulations suggested that Na and Ca are involved in the Ivicinity with averaged derived coordination number (CN) of 3.6 and 2.0 and bond length to the nearest neighbour (r X-I ) 2.98 and 2.85 Å, respectively. These results suggest that the coexistence of both Iand I 5+ species is not requested for electric neutrality but instead, we explain the I speciation by the possible interplay with oxygen species from the borosilicate matrix. In addition, the results imply that the borosilicate network is affected by the I dissolution.

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“…7 Niobium oxo-cluster chemistry has experienced great success in the past decade and new compounds beyond {Nb6} and {Nb10} 25 have been characterized. In fact, just the list of isopolyoxoniobates has increased considerably: ([Nb7O22] 9-; {Nb7}, Figure 1b) 26 , ([Nb24O72H9] 9-; {Nb24}, Figure 1h), 27 ([HNb27O76] 16-; {Nb27}), 28 [Nb32O96] 32-, 29 [Nb52O150] 40-, 30 and [Nb54O151] These discoveries have important implications in expanding the main applications of niobium oxo-clusters in radioactive waste management 32 and catalysis. 33,34 On the other hand, polyoxotantalate chemistry remains underexplored, partly due to slow reaction kinetics and poor solubility in water.…”

Section: Introductionmentioning

confidence: 99%

Computational Prediction of Speciation Diagrams and Nucleation Mechanisms: Molecular Vanadium, Niobium and Tantalum Oxide Nanoclusters in Solution

Petrus

Segado

Bó

2022

Preprint

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Understanding the aqueous speciation of molecular metal-oxo clusters plays a key role in different fields such as catalysis, electrochemistry, nuclear waste recycling, and biochemistry. To accurately describe the speciation, it is essential to elucidate the underlying self-assembly processes. Herein, we apply a computational method to predict the speciation and formation mechanisms of polyoxovanadates, -niobates and -tantalates. While polyoxovanadates have been widely studied, polyoxoniobates and -tantalates lack the same level of understanding. In the first place, we proposed a pentavanadate cluster ([V5O14]3-) as a key intermediate for the formation of the decavanadate. Our computed phase speciation diagram is in particularly good agreement with the experiments. Secondly, we report the formation constants of the heptaniobate, [Nb7O22]9-, decaniobate, [Nb10O28]6-, and tetracosaniobate [H9Nb24O72]9-. Additionally, we have computed the speciation and phase diagram of niobium, which so far was restricted to Lindqvist derivates. Finally, we have predicted the formation constant of the decatantalate ([Ta10O26]6-) in water, even though it had only been synthetized in toluene. Furthermore, the corresponding speciation and phase diagrams for polyoxotantalates have been also calculated. Overall, we show that our method can be successfully applied to different families of molecular metal oxides without any need for readjustments; therefore, it can be regarded as a trustworthy tool for exploring polyoxometalates’ chemistry.

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Niobium- and bismuth-silver phosphate glasses for the conditioning of radioactive iodine

Cited by 17 publications

References 29 publications

The influence of iodide on glass transition temperature of high‐pressure nuclear waste glasses

The influence of iodide on glass transition temperature of high‐pressure nuclear waste glasses

Iodine local environment in high pressure borosilicate glasses: An X-ray photoelectron spectroscopy and X-ray absorption spectroscopy investigation

Computational Prediction of Speciation Diagrams and Nucleation Mechanisms: Molecular Vanadium, Niobium and Tantalum Oxide Nanoclusters in Solution

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