Phase separation and crystallization effects on the structure and durability of molybdenum borosilicate glass

Nicoleau, Elodie; Schuller, S.; Angeli, Frédéric; Charpentier, Thibault; Jollivet, Patrick; Gac, A. Le; Fournier, Maxime; Mesbah, Adel; Vasconcelos, Filipe

doi:10.1016/j.jnoncrysol.2015.07.001

Cited by 53 publications

(66 citation statements)

References 61 publications

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“…Morphologically, these spheres looked more like “partial moons,” since the volume of the liquid shrank on cooling more extensively than the glass, and the calcium molybdate crystals occupied a smaller volume than that of the spherical liquid phase. This phenomenon had also been observed in previous studies …”

Section: Resultssupporting

confidence: 90%

Crystallization study of rare earth and molybdenum containing nuclear waste glass ceramics

et al. 2019

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A glass‐ceramic waste form is being developed for immobilization of waste streams of alkali (A), alkaline‐earth (AE), rare earth (RE), and transition metals generated by transuranic extraction for reprocessing of used nuclear fuel. Benefits over an alkali borosilicate waste form are realized by the partitioning of the fission product fraction insoluble in glass into a suite of chemically durable crystalline phases through controlled cooling, including (AE,A,RE)MoO4 (powellite) and (RE,A,AE)10Si6O26 (oxyapatite). In this study, a simplified 8‐oxide system (SiO2‐Nd2O3‐CaO‐Na2O‐B2O3‐Al2O3‐MoO3‐ZrO2) was melted, then soaked at various temperatures from 1450 to 1150°C, and subsequently quenched, in order to obtain snapshots into the phase distribution at these temperatures. For these samples, small angle X‐ray and neutron scattering, quantitative X‐ray diffraction, electron microscopy, 23Na nuclear magnetic resonance, Nd3+ visible absorption, and temperature‐dependent viscosity were characterized. In this composition, soak temperatures of ≲1250°C were necessary to nucleate calcium molybdate (~10‐20 nm in diameter). Further cooling produced oxyapatite and total crystallization increased with lower soak temperatures. Both Na and Nd entered the crystalline phases with lower‐temperature soak conditions. Slow cooling or long isothermal treatments at ~975°C produced significantly higher crystal fractions.

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Section: Resultssupporting

confidence: 90%

Crystallization study of rare earth and molybdenum containing nuclear waste glass ceramics

et al. 2019

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“…Journal of Non-Crystalline Solids 473 (2017) [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16] an increase to T PS would cause the lower viscosity separated phase B to coalesce for a longer period of time during cooling forming larger regions. Furthermore, the higher viscosity Si-rich phase would cause the cation-rich phase B deposits to combine into the lowest possible surface area, hence why more spherical deposits are observed with increasing These observations indicate that an analogous theory can be proposed for calcium borosilicate systems, in which increasing [MoO 3 ] also causes an increase in T PS and T C .…”

Section: Kb Patel Et Almentioning

confidence: 99%

“…Journal of Non-Crystalline Solids 473 (2017) [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16] phase, the lattice parameters determined by refinement are initially higher than that of CaMoO 4 monocrystals (a = 5.222 Å and c = 11.425 Å [62]). This observation has been previously recorded for soda-lime borosilicates employing a similar fabrication technique [12,63] and emphasizes how the properties of a glassy phase can increase the lattice energy of embedded crystal phases [64].…”

Section: Kb Patel Et Almentioning

confidence: 99%

“…Moreover, they can be synthesized at reasonable conditions and show good chemical stability when subjected to aqueous environments [1,3]. Though they have proved beneficial in many regards, there are material limitations introduced by insoluble species that can result in unexpected phase separation [4][5][6] and thus degradation of physical properties [7,8].…”

Section: Introductionmentioning

confidence: 99%

“…For the first 100 to 300 years of high-level waste storage, β-decay will provide a higher ionization dose than α-decay [26], thus resulting in significant alteration to the encapsulating structure. The dose from β-decay will then reach a plateau from 100 to 10 6 years of storage given current waste loading for French nuclear waste glasses. In organized systems such as metals or crystals, accelerated external radiation used to replicate these events can induce dislocations and eventual cracking along stress planes, as well as swelling and void formation [7,26].…”

Section: Introductionmentioning

confidence: 99%

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Impacts of composition and beta irradiation on phase separation in multiphase amorphous calcium borosilicates

Patel

Boizot

Facq

et al. 2017

Journal of Non-Crystalline Solids

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A B S T R A C TBorosilicate glasses for nuclear waste applications are limited in waste loading by the precipitation of watersoluble molybdates. In order to increase storage efficiency, new compositions are sought out that trap molybdenum in a water-durable CaMoO 4 crystalline phase. Factors affecting CaMoO 4 combination and glass-inglass phase separation in calcium borosilicate systems as a function of changing [MoO 3 ] and [B 2 O 3 ] are examined in this study in order to understand how competition for charge balancers affects phase separation. It further examines the influence of radiation damage on structural modifications using 0.77 to 1.34 GGy of 2.5 MeV electron radiation that replicates inelastic collisions predicted to occur over long-term storage. The resulting microstructure of separated phases and the defect structure were analyzed using electron microscopy, XRD, Raman and EPR spectroscopy prior to and post irradiation. Synthesized calcium borosilicates are observed to form an unusual heterogeneous microstructure composed of three embedded amorphous phases with a solubility limit~2.5 mol% MoO 3. Increasing [B 2 O 3 ] increased the areas of immiscibility and order of (MoO 4 ) 2 − anions, while increasing [MoO 3 ] increased both the phase separation and crystallization temperature resulting in phases closer to metastable equilibrium, and initiated clustered crystallization for [MoO 3 ] > 2.5 mol%. β-irradiation was found to have favorable properties in amorphous systems by creating structural disorder and defect assisted ion migration that thus prevented crystallization. It also increased reticulation in the borosilicate network through 6-membered boroxyl ring and Si ring cleavage to form smaller rings and isolated units. This occurred alongside an increased reduction of Mo 6 + with dose that can be correlated to molybdenum solubility.In compositions with existing CaMoO 4 crystallites, radiation caused a scattering effect, though the crystal content remained unchanged. Therefore β-irradiation can preferentially prevent crystallization in calcium borosilicates for [MoO 3 ] < 2.5 mol%, but has a smaller impact on systems with existing CaMoO 4 crystallites.

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Recent progress in solid‐state nuclear magnetic resonance of half‐integer spin low‐γ quadrupolar nuclei applied to inorganic materials

Smith

2020

Magnetic Reson in Chemistry

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An overview is presented of recent progress in the solid-state nuclear magnetic resonance (NMR) observation of low-γ nuclei, with a focus on applications to inorganic materials. The technological and methodological advances in the last 20 years, which have underpinned the increased accessibility of low-γ nuclei for study by solid-state NMR techniques, are summarised, including improvements in hardware, pulse sequences and associated computational methods (e.g., first principles calculations and spectral simulation). Some of the key initial observations from inorganic materials of these nuclei are highlighted along with some recent (most within the last 10 years) illustrations of their application to such materials. A summary of other recent reviews of the study of low-γ nuclei by solid-state NMR is provided so that a comprehensive understanding of what has been achieved to date is available.

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Phase separation and crystallization effects on the structure and durability of molybdenum borosilicate glass

Cited by 53 publications

References 61 publications

Crystallization study of rare earth and molybdenum containing nuclear waste glass ceramics

Crystallization study of rare earth and molybdenum containing nuclear waste glass ceramics

Impacts of composition and beta irradiation on phase separation in multiphase amorphous calcium borosilicates

Recent progress in solid‐state nuclear magnetic resonance of half‐integer spin low‐γ quadrupolar nuclei applied to inorganic materials

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