Microstructure of Powellite‐Rich Glass‐Ceramics: A Model System for High Level Waste Immobilization

Taurines, Tatiana; Boizot, Bruno

doi:10.1111/j.1551-2916.2011.05015.x

Cited by 40 publications

(41 citation statements)

References 18 publications

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“…Due to their better thermodynamic, chemical and radiation durability, ceramic based matrices are proposed to be the alternate hosts for nuclear waste forms [1,2]. On these lines, 'Ti' based SYNROC (synthetic rock) and 'Zr' based pyrochlores are under consideration for their potential use as ceramic hosts for fixing nuclear waste [3][4][5].…”

Section: Introductionmentioning

confidence: 99%

An electron spin resonance and photoluminescence investigation of the effect of annealing temperature on Gd-doped La2Zr2O7 nano-ceramics

Mohapatra¹,

Rajeswari²,

Hon³

et al. 2015

Ceramics International

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Section: Introductionmentioning

confidence: 99%

An electron spin resonance and photoluminescence investigation of the effect of annealing temperature on Gd-doped La2Zr2O7 nano-ceramics

Mohapatra¹,

Rajeswari²,

Hon³

et al. 2015

Ceramics International

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“…While [65] and can be prevented at temperatures around~1050°C [18]. Though a similar synthesis technique was used for all samples in the CB series, properties of this specific glass may have enabled slower internal cooling that thus initiated and propagated dendritic growth.…”

Section: Kb Patel Et Almentioning

confidence: 99%

“…Molybdate formation in particular can be controlled by composition [10,16,17], external heat treatments [12,18,19], redox chemistry [20,21], or by controlled cooling during synthesis [11]. 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].…”

Section: Introductionmentioning

confidence: 99%

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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“…The obtained glass‐ceramics contain powellite crystals well dispersed into the residual glass, with various size distributions and concentrations. Crystal sizes range from a few tens of nanometers to a few micrometers depending on MoO 3 content and heat treatments …”

Section: Introductionmentioning

confidence: 99%

Powellite‐Rich Glass‐Ceramics: A Spectroscopic Study by EPR and Raman Spectroscopy

2013

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International audienceThe aim of this study is to better understand the incorporation of rare earth elements in glass-ceramics of nuclear interest. We synthesized glass-ceramics from glasses in the system SiO 2-B 2 O 3-Na 2 O-CaO-Al 2 O 3-MoO 3-Gd 2 O 3 by various heat treatments. Gadolinium is used both as a spectroscopic probe and as a minor actinide surrogate. Glass-ceramics contain only one crystalline phase in the bulk: powellite (CaMoO 4). This phase can incorporate Gd 3+ and Na + ions by substitutions on the Ca site. We demonstrated that the charge compensation by Na + favors the rare earth elements incorporation. Moreover, the incorporated elements do not seem to be randomly distributed into the powellite structure

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Microstructure of Powellite‐Rich Glass‐Ceramics: A Model System for High Level Waste Immobilization

Cited by 40 publications

References 18 publications

An electron spin resonance and photoluminescence investigation of the effect of annealing temperature on Gd-doped La2Zr2O7 nano-ceramics

An electron spin resonance and photoluminescence investigation of the effect of annealing temperature on Gd-doped La2Zr2O7 nano-ceramics

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

Powellite‐Rich Glass‐Ceramics: A Spectroscopic Study by EPR and Raman Spectroscopy

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