Phase separation and crystallization of borosilicate glass enriched in MoO3, P2O5, ZrO2, CaO

Schuller, S.; Pinet, O.; Grandjean, Agnès; Blisson, T.

doi:10.1016/j.jnoncrysol.2007.07.041

Cited by 56 publications

(52 citation statements)

References 4 publications

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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%

“…Above this solubility limit, it is possible for metastable phases to form leading to crystallization of molybdenum-rich phases [11,12]. The production of alkali molybdates (Na 2 MoO 4 , Cs 2 MoO 4 ), known as yellow phase, are particularly problematic owing to their high water solubility and ability to act as carriers for radioactive cesium and strontium [1,13].…”

Section: Introductionmentioning

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%

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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: Kb Patel Et Almentioning

confidence: 99%

Section: Kb Patel Et Almentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

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

View full text Add to dashboard Cite

show abstract

“…MoO4 2-tends to form alkali or alkaline earth molybdate crystals on separating out from the glass network and therefore the molybdate solubility can be related to the cations with which the MoO4 2-tetrahedra are associated. Tailoring glass composition so as to improve molybdate solubility in borosilicate glasses has been undertaken by a number of workers [2,[14][15][16][17]; however, the solubility is still low. For example, Caurant and co-workers [14,17] have found that increasing the B2O3 level in a Ca-Na borosilicate glass, which is supposed to consume more Na + cations thereby enabling more MoO4 2-units to be connected with Ca 2+ , does not enhance molybdate capacity in glass in reality.…”

Section: Introductionmentioning

confidence: 99%