Rings in Network Glasses: The $$\mathrm{B_2O_3}$$ Case

Ferlat, G.

doi:10.1007/978-3-319-15675-0_14

Cited by 6 publications

(4 citation statements)

References 149 publications

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“…Many other possible corrections to Equation can be conceived, including, for example, the fact that ring and nonring B–Ø b (–B) bridging bonds have slightly different lengths, an effect associated with their different B–Ø b (–B) bond angles. However, as the ring content, or more specifically the bond angle distribution, is challenging to measure in a glass, let alone a melt, such a correction is likely impractical.…”

Section: Discussionmentioning

confidence: 99%

Borate melt structure: Temperature‐dependent B–O bond lengths and coordination numbers from high‐energy X‐ray diffraction

et al. 2018

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Borate melts containing <20 mol% Na 2 O have been studied using high-energy synchrotron X-ray diffraction. Temperature dependencies of the mean B-O bond lengths are shown to vary strongly with soda content, by comparison to previous measurements on liquid B 2 O 3 and Na 2 B 4 O 7 . Whereas in liquid B 2 O 3 linear thermal expansion of the BØ 3 units is observed, with coefficient a BO = 3.7(2) 9 10 À6 K À1 , this expansion is apparently slightly suppressed in melts containing <20 mol% Na 2 O, and is dramatically reversed at the diborate composition. These effects are interpreted in terms of changes in the mean B-O coordination number, where the reaction BØ 4 À + BØ 3 ⇌ BØ 3 + BØ 2 O À shifts to the right with increasing temperature. The empirical bond-valence relationship is used to convert measured bond lengths, r BO , to coordination numbers, n BO , including a correction for the expected thermal expansion. This method is more accurate and precise than direct determination of n BO from peak areas in the radial distribution functions. Gradients of Dn BO / DT = À3.4(3) 9 10 À4 K À1 close to the diborate composition, and Dn BO / DT = À0.3(1) 9 10 À4 K À1 for a 13(3) mol% Na 2 O melt are observed, in reasonable agreement with Raman spectroscopic observations and thermodynamic modeling, with some quantitative differences. These observations go toward explaining isothermal viscosity maxima and changes in fragility across the sodium borate system.

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Section: Discussionmentioning

confidence: 99%

Borate melt structure: Temperature‐dependent B–O bond lengths and coordination numbers from high‐energy X‐ray diffraction

et al. 2018

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“…Diboron trioxide (B 2 O 3 ) not only is the second most used component of industrial glasses after silica (SiO 2 ), but also a canonical network-forming system per se (see, e.g., Refs. [1,2] for reviews). The originality of the lowpressure B 2 O 3 networks, either crystalline or vitreous, stems from their building blocks, which are bidimensional (2D) trigonal (BO 3 ) units.…”

Section: Introductionmentioning

confidence: 99%

“…1 , François-Xavier Coudert 2 , Henri Hay 1 , Francesco Mauri 1,3 , Michele Casula1 1 Sorbonne Université, MNHN, UMR CNRS 7590, IRD, IMPMC, F-75005 Paris, France 2 Chimie ParisTech, PSL University, CNRS, Institut de Recherche de Chimie Paris, 75005 Paris, France 3 Dipartimento di Fisica, Università di Roma La Sapienza, Piazzale Aldo Moro 5, I-00185 Roma, Italy B 2 O 3 polymorphs A total of 27 B 2 O 3 polymorphs (including B 2 O 3 -I) has been investigated: this includes the 26 structures originally considered in Ref. [S1] and a newly constructed one, derived from ideas suggested in Ref.…”

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confidence: 99%

van der Waals forces stabilize low-energy polymorphism in B2O3 : Implications for the crystallization anomaly

Ferlat

Hellgren

Coudert

et al. 2019

Phys. Rev. Materials

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The cohesive energies and structural properties of recently predicted -and never synthesized -B 2 O 3 polymorphs are investigated from first principles using density functional theory and high-accuracy many-body methods, namely, the random phase approximation and quantum Monte Carlo. We demonstrate that the van der Waals forces play a key role in making the experimentally known polymorph (B 2 O 3 -I) the lowest in energy, with many competing metastable structures lying only a few kcal/mol above. Remarkably, all metastable crystals are comparable in energy and density to the glass, while having anisotropic and mechanically soft structures. Furthermore, the best metastable polymorph according to our stability criteria has a structural motif found in both the glass and a recently synthesized borosulfate compound. Our findings provide new perspectives for understanding the B 2 O 3 anomalous behavior, namely, its propensity to vitrify in a glassy structure drastically different from the known crystal. arXiv:1906.10605v1 [cond-mat.mtrl-sci]

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“…Density of B 2 O 3 Glasses. Density is a crucial quantity in the study of glasses 28 because it reflects the packing of atoms. The calculated density of the B 2 O 3 glass versus pressure at room temperature is shown in Figure 1.…”

Section: Resultsmentioning

confidence: 99%

First-Principles Studies on the Structure and B–O Coordination of B₂O₃ Glass at High Pressure

Kuang,

Pan,

Tse

2024

J. Phys. Chem. C

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The structures of amorphous materials at extreme pressures can be very different from those of their crystalline counterparts. Recent nonresonant inelastic scattering experiments on B 2 O 3 glass performed up to ∼120 GPa have suggested that B− O coordination numbers higher than 4 were presented. In this study, B 2 O 3 glass structures up to 350 GPa were generated from first-principles molecular dynamics (FPMD) calculations. X-ray and neutron diffraction patterns, B K-edge X-ray absorption spectra, and 11 B NMR spectra were computed and compared to experiments. The nature of the B−O interactions was characterized by Bader's quantum theory of atoms in molecules (QTAIM) analysis and electron localization function (ELF). The theoretical results found that 5-and 6-coordinated B exists at high pressure. However, not all of the B and O contacts are covalently bonded. Instead, both BO 5 and BO 6 groups consisted of 4 short B−O covalent bonds with weaker B−O interactions with the other O atoms. Structure prediction calculations were performed at a similar pressure range to assess whether 6-coordinated B−O can exist in crystalline B 2 O 3 . No genuine 6-coordinated B was found. The high B−O coordination number in the glass is simply due to compaction at high pressure.

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Rings in Network Glasses: The $$\mathrm{B_2O_3}$$ Case

Cited by 6 publications

References 149 publications

Borate melt structure: Temperature‐dependent B–O bond lengths and coordination numbers from high‐energy X‐ray diffraction

Borate melt structure: Temperature‐dependent B–O bond lengths and coordination numbers from high‐energy X‐ray diffraction

van der Waals forces stabilize low-energy polymorphism in B2O3 : Implications for the crystallization anomaly

First-Principles Studies on the Structure and B–O Coordination of B₂O₃ Glass at High Pressure

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Rings in Network Glasses: The $$\mathrm{B_2O_3}$$ Case

Cited by 6 publications

References 149 publications

Borate melt structure: Temperature‐dependent B–O bond lengths and coordination numbers from high‐energy X‐ray diffraction

Borate melt structure: Temperature‐dependent B–O bond lengths and coordination numbers from high‐energy X‐ray diffraction

van der Waals forces stabilize low-energy polymorphism in B2O3 : Implications for the crystallization anomaly

First-Principles Studies on the Structure and B–O Coordination of B2O3 Glass at High Pressure

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First-Principles Studies on the Structure and B–O Coordination of B₂O₃ Glass at High Pressure