Oxygen triclusters in crystalline CaAl4O7(grossite) and in calcium aluminosilicate glasses:17O NMR

Stebbins, Jonathan F.; Oglesby, Jane V.; Kroeker, Scott

doi:10.2138/am-2001-1019

Cited by 124 publications

(151 citation statements)

References 19 publications

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“…Moreover, a small but significant population of oxygen triclusters is predicted (1%). These findings are in agreement with NMR data on charge-balanced aluminosilicate glasses [29][30][31][32]. In the basaltic liquid (an36di64), the degree of depolymerization of the melt is indicated by the high abundance of NBOs (39.1%), while the population of oxygen triclusters is roughly the same as in rhyolite (~1.2%).…”

Section: Structure Of the Silicate Meltssupporting

confidence: 89%

Electronic redistribution around oxygen atoms in silicate melts by ab initio molecular dynamics simulation

Vuilleumier

Sator

Guillot

2011

Journal of Non-Crystalline Solids

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The structure around oxygen atoms of four silicate liquids (silica, rhyolite, a model basalt and enstatite) is evaluated by ab initio molecular dynamics simulation. Thanks to the use of maximally localized Wannier orbitals to represent the electronic ground state of the simulated system, one is able to quantify the redistribution of electronic density around oxygen atoms as a function of the cationic environment and melt composition. It is shown that the structure of the melt in the immediate vicinity of the oxygen atoms modulates the distribution of the Wannier orbitals associated with oxygen atoms. In particular the evaluation of the distances between the oxygen-core and the orbital Wannier centers and their evolution with the nature of the cation indicates that the Al-O bond in silicate melts is certainly less covalent than the Si-O bond while for the series Mg-O, Ca-O, Na-O and K-O the covalent character of the M-O bond diminishes rapidly to the benefit of the ionic character. Furthermore it is found that the distribution of the oxygen dipole moment coming from the electronic polarization is only weakly dependent on the melt composition, a finding which could explain why some empirical force fields can exhibit a high degree of transferability with melt composition.

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Section: Structure Of the Silicate Meltssupporting

confidence: 89%

Electronic redistribution around oxygen atoms in silicate melts by ab initio molecular dynamics simulation

Vuilleumier

Sator

Guillot

2011

Journal of Non-Crystalline Solids

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“…16,22) However, in this CaO-P 2 O 5 -SiO 2 slag system, oxygen tricluster was not found, this is probably because the content of CaO is high, which increases the difficulty of forming complicated clusters and anions. The distributions of the BO, NBO and O 2¹ are presented in Fig.…”

Section: The Partial Radial Distribution Function (Rdf) and Coordinatmentioning

confidence: 76%

Molecular Dynamics Analysis of the Microstructure of the CaO-P2O5-SiO2 Slag System with Varying P2O5/SiO2 Ratios

Fan

Diao

et al. 2015

Mater. Trans.

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The structures of the CaO-P 2 O 5 -SiO 2 slag system with varying P 2 O 5 /SiO 2 ratios at a fixed CaO content have been investigated by molecular dynamics simulation using the pairwise potential model. The results showed that the average bond lengths of Si-O and P-O were 1.610 « 0.001 ¡ and 1.531 « 0.005 ¡ in the examined range of the P 2 O 5 /SiO 2 ratio. More than 95% Si and P ions were 4-coordinated and formed tetrahedral structures. Average coordination numbers of P-O and Si-O decreased slightly while average coordination number of Ca-O revealed a rising trend with the addition of P 2 O 5 . The non-bridging oxygens (Si-O-Ca and P-O-Ca) were the overwhelming majority and further increased with the substitution of SiO 2 by P 2 O 5 , which results in the decrease of the polymerization constant K p . The numbers of Si and P groups linked to a tagged Si or P tetrahedron (Q n speciation) characterized the polymerization degree of the slag system. The Q 0 of both P and Si declined remarkably with the increase of P 2 O 5 . Correspondingly, () of Si and P increased observably, implying that the polymerization degree of the slag system was enhanced.

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“…The oxygen triclusters have been widely investigated about their existence, 18,30) conformation, 31) quantity 12,13) and influences on dynamics properties.…”

Section: Bos Nbos and Oxygen Triclustersmentioning

confidence: 99%

“…Furthermore, the 'Al avoidance' principle has been debated in literature regarding its accuracy and the range of application. Structural defects such as non-bridging oxygen, 12,15) tricluster 11,[16][17][18] and Al V 19-21) also occupy considerable quantities and have deep influences on the system's structure and properties. In this paper, MD (Molecular Dynamic) simulation is applied to the CAS slags at a fixed CaO content and various molar ratios between SiO2 (64% to 24%) and Al2O3 (6% to 46%) to promote understanding the change of the primary structural properties with varying Al2O3/SiO2 ratios, including partial radial distribution function (RDF), coordination number (CN), distributions of different types of oxygen, bond lengths and bond angles.…”

Section: Introductionmentioning

confidence: 99%

Molecular Dynamics Study of the Structural Properties of Calcium Aluminosilicate Slags with Varying Al2O3/SiO2 Ratios

et al. 2012

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Molecular dynamics simulation was explored to investigate the change of structure of calcium aluminosilicate slags with varying Al2O3/SiO2 ratios at a fixed CaO content. In practice the results of the study are relevant to the significant changes in slag structure caused by the changes in chemical composition during continuous casting of steels containing high amounts of dissolved aluminum. It was found that Q 4 tetrahedral species (tetrahedron with four bridging oxygens) increase while NBOs (non-bridging oxygen) decreases with increasing Al2O3/SiO2 mole ratio, suggesting that a more polymerized network was formed. The concentration of oxygen tricluster increased dramatically up to 24% with increasing Al2O3/SiO2 mole ratio, and the coordination number for Al (CNAl-O) was also observed to increase from 4.02 for sample CAS1 to 4.11 for sample CAS11, suggesting that high coordination number of Al presents in the slag melt with the substitution of [AlO4] for [SiO4]. NBOs prefer to be coordinated with Si and Al tends to be localized in more polymerized environment as network intermediate phases. The degree of Al avoidance was calculated and the Al avoidance principle is applicable in the SiO2 rich regions.KEY WORDS: molecular dynamics; calcium aluminosilicate slag; slag structure; Al2O3/SiO2 ratio.

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Oxygen triclusters in crystalline CaAl₄O₇(grossite) and in calcium aluminosilicate glasses:¹⁷O NMR

Cited by 124 publications

References 19 publications

Electronic redistribution around oxygen atoms in silicate melts by ab initio molecular dynamics simulation

Electronic redistribution around oxygen atoms in silicate melts by ab initio molecular dynamics simulation

Molecular Dynamics Analysis of the Microstructure of the CaO-P<sub>2</sub>O<sub>5</sub>-SiO<sub>2</sub> Slag System with Varying P<sub>2</sub>O<sub>5</sub>/SiO<sub>2</sub> Ratios

Molecular Dynamics Study of the Structural Properties of Calcium Aluminosilicate Slags with Varying Al2O3/SiO2 Ratios

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