The structure of vitreous and liquid boron oxide

Krogh-Moe, J.

doi:10.1016/0022-3093(69)90025-8

Cited by 314 publications

(98 citation statements)

References 19 publications

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“…Krogh-Moe and Walrafen et al observed a similar reduction in intensity of the Raman boroxyl mode for vitreous boron oxide heat treated from 260 to 1000°C, where thermal events resulted in a structural reorganization of primarily boroxyl groups to a random network of BO 3 triangles [41,46]. Thus β-irradiation is predicted to replicate certain temperature based effects and cause larger ring cleavage and reformation of smaller rings in both B-rich and Si-rich regions.…”

Section: Radiation Effectsmentioning

confidence: 65%

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: Radiation Effectsmentioning

confidence: 65%

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 Raman peak B around 800 cm À1 was assigned to a breathing vibration of boroxy rings. [24][25][26][27][28] The boroxy rings are equilibrated with isolated BO 3 units in the liquid borosilicate.…”

Section: Methodsmentioning

confidence: 99%

Oxidation of Boron Carbide-Silicon Carbide Composite at 1073 to 1773 K

et al. 2003

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The oxidation behavior of B 4 C-(25-60 mol%)SiC composites prepared by arc-melting was investigated in the temperature range of 1073 to 1773 K using a thermogravimetric technique. Liquid borosilicate, solid SiO 2 and carbon were identified as oxidation products by X-ray diffraction and Raman spectroscopy. Mass gain was observed during oxidation at 1073 K, while mass loss due to the vaporization of boron oxide in liquid borosilicate was observed at temperatures of 1273 K and higher. In situ Raman spectra of the surface of B 4 C-SiC composites indicated that the silica concentration in the liquid borosilicate increased with increasing SiC content in the composite. Micro-Raman spectroscopy showed that carbon was enriched in the borosilicate layer close to the oxide/composite interface. The parabolic rate constants for B 4 C-50 mol%SiC composites at 1073 K were proportional to ambient oxygen partial pressures ranging between 30 and 100 kPa. The diffusion of oxygen molecules through the liquid borosilicate layer could be the rate-controlling process. The increase of SiC content in the B 4 C-SiC composites improved the oxidation resistance in both the mass gain and mass loss regions.

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“…The band 535 -550 cm -1 may be due to vibrations of sodium cations through the glass network. The band 665 -695 cm -1 can be attributed to bending vibrations of BO 3 triangles and stretching vibrations of BO 3 units with non bridging oxygens respectively [11][12][13][14]. The band that appears around 1050 cm -1 can be due to stretching of the BO 4 structural units [15].…”

Section: Ftir Analysismentioning

confidence: 99%

Synthesis and Optical Characterization of Silver Doped Sodium Borate Glasses

Sharma¹,

Singh²,

Mudahar³

et al. 2012

NJGC

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Silver doped sodium borate glasses prepared by melt-quenching technique were checked by XRD technique for their amorphous nature. It is observed that the molar volume increases with increasing Ag 2 O content leading to open structure. Fourier Transform Infrared spectroscopy (FTIR) reveals the formation of BO 3 and BO 4 groups upon addition of silver oxide as modifier. From the Ultraviolet-Visible (UV-VIS) absorption spectra it is seen that the optical band gap increases with the increase of Ag 2 O content. Urbach energy is observed between 0.55 -0.77 eV. The results obtained from molar volume, Fourier Transform Infrared spectroscopy and band gap energy measurements are in agreement with each other and nearly give the similar information about the studied glasses.

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The structure of vitreous and liquid boron oxide

Cited by 314 publications

References 19 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

Oxidation of Boron Carbide-Silicon Carbide Composite at 1073 to 1773 K

Synthesis and Optical Characterization of Silver Doped Sodium Borate Glasses

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