Structural control on bulk melt properties: Single and double quantum 29Si NMR spectroscopy on alkali-silicate glasses

Malfait, Wim J.; Halter, Werner E.; Morizet, Yann; Meier, Beat H.; Verel, René

doi:10.1016/j.gca.2007.09.011

Cited by 88 publications

(112 citation statements)

References 60 publications

(79 reference statements)

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“…[11][12][13] In contrast with the lack of evidence for the Sawyer reassignment, the conventional assignment of the 29 Si NMR peaks, based on the presence Q 2= in three-membered rings in the spectra of potassium, rubidium, and cesium silicate glasses, is supported by a wide variety of evidence, 5 despite claims to the contrary by Sawyer et al 1 Among others, the spectral properties, most notably linewidth, peak position, and relative weakness of the J-coupling, are fully consistent with a Q 2 species with narrow Si-O-Si angles typical for three-membered rings. 5 Two-dimensional homonuclear correlation 29 Si NMR data also confirm this interpretation. 5 In addition, crystalline K 2 SiO 3 , Rb 2 SiO 3 , and Cs 2 SiO 3 consist entirely of Q 2 in three-membered rings.…”

Section: Si Nmr Band Assignmentmentioning

confidence: 72%

“…5 Two-dimensional homonuclear correlation 29 Si NMR data also confirm this interpretation. 5 In addition, crystalline K 2 SiO 3 , Rb 2 SiO 3 , and Cs 2 SiO 3 consist entirely of Q 2 in three-membered rings. 14 Furthermore, the D2 Raman band near 600 cm −1 , related to three-membered rings, 15 is much more intense in potassium, rubidium, and cesium silicate glasses compared with other silicate glasses.…”

Section: Si Nmr Band Assignmentmentioning

confidence: 72%

“…1a and 1b). The original assignment 4,5 considers the additional peak to be due to a special type of Q 2 (labeled Q 2= ); the reassignment by Sawyer et al 1 considers an additional peak to be due to a second type of Q 3 (labeled Q 3 *).…”

Section: Si Nmr Band Assignmentmentioning

confidence: 99%

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Comment on “Spectroscopic studies of oxygen speciation in potassium silicate glasses and melts”

Malfait

2015

Can. J. Chem.

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Recent O1s XPS studies suggest that significant free oxide (O 2-or K-O-K) is present in potassium silicate glasses, in contrast with what was concluded from 29 Si and 17 O solid-state NMR data. An alternative peak assignment of the Q n peaks in the 29 Si NMR spectra was proposed to bring the 29 Si NMR data in line with the O1s data, but this reassignment (i) is not supported by any evidence other than the resulting agreement between the NMR and XPS data, (ii) is at odds with the spectral properties of the bands (peak position and width), (iii) ignores the strong evidence for the original peak assignment, and (iv) results in highly implausible equilibrium constants for the Q n speciation reactions. More likely causes for the apparent discrepancy between the XPS and NMR data are the incorrect estimation of the precision of the bridging oxygen content from the O1s XPS data, the systematic overestimation of the bridging oxygen content from the O1s XPS data, and (or) the incorrect estimation of the accuracy of the compositional analysis, which was based on the precision rather than the accuracy of the electron microprobe analysis. Thus, the available evidence strongly suggests that the original assignment of the 29 Si NMR spectra is correct. Neither the 29 Si NMR nor the O1s XPS data support the presence of significant amounts of free oxide in potassium silicate glasses with K 2 O/SiO 2 Ͻ Ͻ 2.Key words: potassium silicate glasses, free oxygen, O1s XPS, 29 Si NMR, peak assignment. Résumé :De récentes études en XPS de l'oxygène O1s semblent indiquer la présence importante d'oxyde libre (O 2-ou K-O-K) dans les verres de silicate de potassium, contrairement aux conclusions issues des données RMN 29 Si et 17 O à l'état solide. On y a proposé une attribution différente des pics des espèces Q n dans les spectres RMN 29 Si afin de mettre les données RMN du silicium 29 Si en conformité avec les données XPS de l'oxygène O1s. Toutefois, cette réattribution (i) n'est appuyée par aucune preuve autre que la correspondance résultante entre les données RMN et XPS, (ii) est en désaccord avec les propriétés spectrales des bandes (position et largeur des pics), (iii) fait abstraction des fortes indications appuyant l'attribution originale des pics et (iv) génère des constantes d'équilibre hautement improbables relativement aux réactions de spéciation Q n . Il apparaît plus probable que les incohérences apparentes entre les données XPS et RMN soient dues à une estimation erronée de la précision de la proportion d'atomes d'oxygène pontants à partir des données XPS O1s, à la surestimation systématique de la proportion d'atomes d'oxygène pontants à partir des données XPS O1s et (ou) à l'estimation erronée de l'exactitude de l'analyse élémentaire, laquelle était fondée sur la précision plutôt que sur l'exactitude de l'analyse par microsonde électronique. Par conséquent, l'ensemble des éléments probants dont on dispose laisse fortement supposer que l'attribution originale des spectres RMN 29 Si était correcte. Ni les données RMN ...

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Section: Si Nmr Band Assignmentmentioning

confidence: 72%

Section: Si Nmr Band Assignmentmentioning

confidence: 72%

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Comment on “Spectroscopic studies of oxygen speciation in potassium silicate glasses and melts”

Malfait

2015

Can. J. Chem.

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“…Five cesium silicate glasses with alkali contents from 25 to 40 mol% were prepared by mixing appropriate proportions of SiO 2 and cesium di-or metasilicate glass (samples 20 and 21 from an earlier study). [10] Batches of 0.5 g were then melted for 15 to 30 min at 100 K above their liquidus temperature and quenched by dipping the bottom of the platinum crucible in water (quench rate 200-500 K/s). The melting time was kept short to avoid unnecessary loss of Cs from the melt; the low viscosity of these depolymerized glasses ensured sample homogeneity.…”

Section: Methodsmentioning

confidence: 99%

“…of three-membered rings in alkali silicate glasses determined by 29 Si NMR spectroscopy. [10] The peaks associated with the various Q n species are observed in the 900-1200 cm −1 range. For all Cs 2 O contents, a dominant peak near 1100 cm −1 is present.…”

Section: Qualitative Descriptionmentioning

confidence: 98%

Quantitative Raman spectroscopy: speciation of cesium silicate glasses

Malfait

2009

J Raman Spectroscopy

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The silicate speciation forms an important aspect of the structure of silicate melts, a subject of interest to both the earthand materials science communities. In this study, the Q n speciation of binary cesium silicate glasses was studied by Raman spectroscopy. A method to extract the equilibrium constant from a set of Raman spectra is presented, and the least-squares optimization algorithm is given (in Supporting Information). Log(K), the equilibrium constant of the speciation reaction, 2Q 3 = Q 4 + Q 2 , equals −2.72 ± 0.11 at the glass transition. This extends the previously established correlation between log(K) and the inverse of the ionic radius of the network modifier to cesium.

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Turning Coacervates into Biohybrid Glass: Core/Shell Capsules Formed by Silica Precipitation in Protein/Polysaccharide Scaffolds

et al. 2013

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Kern‐Schale‐Biohybridkapseln (siehe Bild), die flüchtige Verbindungen verkapseln können, entstehen durch Fällung von amorphem Siliciumdioxid in einem Protein‐Polyanion‐Koazervatgerüst. Dieses Gerüst gibt der Kapselhülle ihre endgültige Form und Struktur und stellt eine acide Mikroumgebung bereit, in der die Hydrolyse und Kondensation flüssiger Siliciumdioxidvorstufen lokal induziert werden können.

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Structural control on bulk melt properties: Single and double quantum 29Si NMR spectroscopy on alkali-silicate glasses

Cited by 88 publications

References 60 publications

Comment on “Spectroscopic studies of oxygen speciation in potassium silicate glasses and melts”

Comment on “Spectroscopic studies of oxygen speciation in potassium silicate glasses and melts”

Quantitative Raman spectroscopy: speciation of cesium silicate glasses

Turning Coacervates into Biohybrid Glass: Core/Shell Capsules Formed by Silica Precipitation in Protein/Polysaccharide Scaffolds

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