Sen, S. ; Widgeon, S. J. ; Navrotsky, A. ; Mera, G. ; Tavakoli, A. ; Ionescu, E. ; Riedel, R. (2013)
Carbon substitution for oxygen in silicates in planetary interiors.
In: Proceedings of the National Academy of Sciences, 110 (40)
doi: 10.1073/pnas.1312771110
Artikel, Bibliographie
Kurzbeschreibung (Abstract)
Amorphous silicon oxycarbide polymer-derived ceramics (PDCs), synthesized from organometallic precursors, contain carbon- and silica-rich nanodomains, the latter with extensive substitution of carbon for oxygen, linking Si-centered SiOxC4-x tetrahedra. Calorimetric studies demonstrated these PDCs to be thermodynamically more stable than a mixture of SiO2, C, and silicon carbide. Here, we show by multinuclear NMR spectroscopy that substitution of C for O is also attained in PDCs with depolymerized silica-rich domains containing lithium, associated with SiOxC4-x tetrahedra with nonbridging oxygen. We suggest that significant (several percent) substitution of C for O could occur in more complex geological silicate melts/glasses in contact with graphite at moderate pressure and high temperature and may be thermodynamically far more accessible than C for Si substitution. Carbon incorporation will change the local structure and may affect physical properties, such as viscosity. Analogous carbon substitution at grain boundaries, at defect sites, or as equilibrium states in nominally acarbonaceous crystalline silicates, even if present at levels at 10–100 ppm, might form an extensive and hitherto hidden reservoir of carbon in the lower crust and mantle.
| Typ des Eintrags: | Artikel |
|---|---|
| Erschienen: | 2013 |
| Autor(en): | Sen, S. ; Widgeon, S. J. ; Navrotsky, A. ; Mera, G. ; Tavakoli, A. ; Ionescu, E. ; Riedel, R. |
| Art des Eintrags: | Bibliographie |
| Titel: | Carbon substitution for oxygen in silicates in planetary interiors |
| Sprache: | Englisch |
| Publikationsjahr: | 22 August 2013 |
| Titel der Zeitschrift, Zeitung oder Schriftenreihe: | Proceedings of the National Academy of Sciences |
| Jahrgang/Volume einer Zeitschrift: | 110 |
| (Heft-)Nummer: | 40 |
| DOI: | 10.1073/pnas.1312771110 |
| Kurzbeschreibung (Abstract): | Amorphous silicon oxycarbide polymer-derived ceramics (PDCs), synthesized from organometallic precursors, contain carbon- and silica-rich nanodomains, the latter with extensive substitution of carbon for oxygen, linking Si-centered SiOxC4-x tetrahedra. Calorimetric studies demonstrated these PDCs to be thermodynamically more stable than a mixture of SiO2, C, and silicon carbide. Here, we show by multinuclear NMR spectroscopy that substitution of C for O is also attained in PDCs with depolymerized silica-rich domains containing lithium, associated with SiOxC4-x tetrahedra with nonbridging oxygen. We suggest that significant (several percent) substitution of C for O could occur in more complex geological silicate melts/glasses in contact with graphite at moderate pressure and high temperature and may be thermodynamically far more accessible than C for Si substitution. Carbon incorporation will change the local structure and may affect physical properties, such as viscosity. Analogous carbon substitution at grain boundaries, at defect sites, or as equilibrium states in nominally acarbonaceous crystalline silicates, even if present at levels at 10–100 ppm, might form an extensive and hitherto hidden reservoir of carbon in the lower crust and mantle. |
| Freie Schlagworte: | carbon in silicates, Li-Si-O-C ceramics, deep Earth |
| Fachbereich(e)/-gebiet(e): | 11 Fachbereich Material- und Geowissenschaften > Materialwissenschaft > Fachgebiet Disperse Feststoffe 11 Fachbereich Material- und Geowissenschaften > Materialwissenschaft 11 Fachbereich Material- und Geowissenschaften |
| Hinterlegungsdatum: | 20 Feb 2014 13:36 |
| Letzte Änderung: | 20 Feb 2014 13:36 |
| PPN: | |
| Sponsoren: | This study was performed within a National Science Foundation (NSF) Materials World Network collaborative project entitled “Nanostructure and thermodynamics of polymer-derived ceramics” and was supported by NSF Grant MWN-0906070. |
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