Effect of compositional variations on charge compensation of AlO4 and BO4 entities and on crystallization tendency of a rare-earth-rich aluminoborosilicate glass

Quintas, Arnaud; Caurant, Daniel; Majérus, Odile; Charpentier, Thibault; Dussossoy, Jean-Luc

doi:10.1016/j.materresbull.2009.05.009

Cited by 51 publications

(76 citation statements)

References 14 publications

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“…It is observed that an increase of B 2 O 3 will reduce the tendency of Na 2 MoO 4 crystallization and increase the crystallization of CaMoO 4 in soda-lime borosilicates [10,24]. A similar effect has also been observed when the concentration of CaO is increased, owing to a corresponding reduction of (BO 4 ) − species [10,22]. Increasing the quench rate to 10 4°C .min − 1 has also been observed to promote the growth of CaMoO 4 over alkali molybdates and increase molybdenum solubility up to 2.5 mol% MoO 3 [12].…”

Section: Introductionmentioning

confidence: 66%

“…The higher field strength of Ca 2 + relative to Na + could be promoting the separation of Mo 6 + , hence the observed heterogeneity. Quintas theorized that increasing the modifier field strength would promote the formation of NBOs in the silica network via changes to the boron coordination [22] and thus encourage phase separation. Correspondingly, we can conclude that in the absence of alkali ions the phase separation tendencies increase with only Ca ions present, as it affects both the separation of Mo 6 + and glass-in-glass separation.…”

Section: Kb Patel Et Almentioning

confidence: 99%

“…Compositionally, the preferential charge balancing of (BO 4 ) − and (MoO 4 ) 2 − anionic entities by Na + and Ca 2 + cations can determine molybdate speciation and network connectivity [22]. Due to charge, mobility, size and sterics (BO 4 ) − prefers Na + ions as charge balancers.…”

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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Section: Introductionmentioning

confidence: 66%

Section: Kb Patel Et Almentioning

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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“…the extent of chemical disorder and its influence on the geometrical disorder. [6 -9] Indeed binary borosilicate glasses contains only four-coordinated silicon [4] Si (SiO 4 ) and threecoordinated boron [3] B (BO 3 ) as framework unit. In contradiction with earlier models for such glasses predicting high phase separation, 11 B MQMAS NMR [9] and particularly 17 O MQMAS NMR [6] data showed that the mixing between SiO 2 and B 2 O 3 is prominent.…”

Section: Introductionmentioning

confidence: 99%

“…In contradiction with earlier models for such glasses predicting high phase separation, 11 B MQMAS NMR [9] and particularly 17 O MQMAS NMR [6] data showed that the mixing between SiO 2 and B 2 O 3 is prominent. Even for glasses with Si/B ratios very different from unity, a large amount of [4] Si-O- [3] B linkages is observed by 17 O NMR elucidating the extent of the chemical disorder. However more subtle structural features such as the bond angle distribution are much more difficult to extract from NMR data.…”

Section: Introductionmentioning

confidence: 99%

Contribution of first-principles calculations to multinuclear NMR analysis of borosilicate glasses

et al. 2010

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Boron-11 and silicon-29 NMR spectra of xSiO(2)-(1-x)B(2)O(3) glasses (x=0.40, 0.80 and 0.83) have been calculated using a combination of molecular dynamics (MD) simulations with density functional theory (DFT) calculations of NMR parameters. Structure models of 200 atoms have been generated using classical force fields and subsequently relaxed at the PBE-GGAlevel of DFT theory. The gauge including projector augmented wave (GIPAW) method is then employed for computing the shielding and electric field gradient tensors for each silicon and boron atom. Silicon-29 MAS and boron-11 MQMAS NMR spectra of two glasses (x=0.40 and 0.80) have been acquired and theoretical spectra are found to well agree with the experimental data. For boron-11, the NMR parameter distributions have been analysed using a Kernel density estimation (KDE) approach which is shown to highlight its main features. Accordingly, a new analytical model that incorporates the observed correlations between the NMR parameters is introduced. It significantly improves the fit of the (11)B MQMAS spectra and yields, therefore, more reliable NMR parameter distributions. A new analytical model for a quantitative description of the dependence of the silicon-29 and boron-11 isotropic chemical shift upon the bond angles is proposed, which incorporates possibly the effect of SiO(2)-B(2)O(3) intermixing. Combining all the above procedures, we show how distributions of Si-O-T and B-O-T (T=Si, B) bond angles can be estimated from the distribution of isotropic chemical shift of silicon-29 and boron-11, respectively.

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Structure Characterizations and Molecular Dynamics Simulations of Melt, Glass, and Glass Fibers

Charpentier¹,

Yue³

et al. 2021

Fiberglass Science and Technology

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Effect of compositional variations on charge compensation of AlO4 and BO4 entities and on crystallization tendency of a rare-earth-rich aluminoborosilicate glass

Cited by 51 publications

References 14 publications

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

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

Contribution of first-principles calculations to multinuclear NMR analysis of borosilicate glasses

Structure Characterizations and Molecular Dynamics Simulations of Melt, Glass, and Glass Fibers

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