Hung, Ivan ; Ionescu, Emanuel ; Sen, Jishnu ; Gan, Zhehong ; Sen, Sabyasachi (2021)
Structure and Connectivity in an Amorphous Silicon Oxycarbide Polymer-Derived Ceramic: Results from 2D 29Si NMR Spectroscopy.
In: The Journal of Physical Chemistry C, 125 (8)
doi: 10.1021/acs.jpcc.0c09860
Artikel, Bibliographie
Kurzbeschreibung (Abstract)
The atomic structure of the Si-O-C tetrahedral network of an amorphous silicon oxycarbide polymer-derived ceramic (PDC) of the composition SiO0.94 +/- 0.11 C-1.13 +/- 0.08 was studied at both the short range and the intermediate range using 1D and 2D Si-29 nuclear magnetic resonance (NMR) spectroscopic techniques, respectively . The 1D Si-29 magic angle-spinning NMR spectrum of the PDC indicates that the Si-O-C network consists of SiO4, SiO3C, SiO2C2, and SiC4 units with relative abundances of approximately 26, 25, 20, and 29%, respectively. The 2D Si-29 extended CSA amplification spectrum of this PDC shows that the chemical shift anisotropy (Delta) of the mixed-bond SiOxC4-x units is significantly higher than that of the SiO4 units. On the other hand, the unusually high Delta-value for the SiC4 units was interpreted to be indicative of its role as the connecting element between the Si-O-C network and the free-carbon nanodomains. The 2D Si-29 double-quantum correlation NMR spectrum of this PDC indicates that there is extensive direct linking between SiO4 and SiO3C units in the Si-O-C network besides the connectivity between like SiOxC4-x units, while the SiO4 and SiO2C2 units are only linked via a SiO3C unit. In contrast, the SiO3C units show no restriction in linking with the other SiOxC4-x units in the network. Finally, the SiC4 units show significant clustering, which is consistent with their spatial localization at the interface between the Si-O-C network and the sp(2) C nanodomains. Such a spatial distribution of the SiOxC4-x units is argued to be consistent with their mass-fractal dimensions measured in previous studies.
| Typ des Eintrags: | Artikel |
|---|---|
| Erschienen: | 2021 |
| Autor(en): | Hung, Ivan ; Ionescu, Emanuel ; Sen, Jishnu ; Gan, Zhehong ; Sen, Sabyasachi |
| Art des Eintrags: | Bibliographie |
| Titel: | Structure and Connectivity in an Amorphous Silicon Oxycarbide Polymer-Derived Ceramic: Results from 2D 29Si NMR Spectroscopy |
| Sprache: | Englisch |
| Publikationsjahr: | 4 März 2021 |
| Titel der Zeitschrift, Zeitung oder Schriftenreihe: | The Journal of Physical Chemistry C |
| Jahrgang/Volume einer Zeitschrift: | 125 |
| (Heft-)Nummer: | 8 |
| DOI: | 10.1021/acs.jpcc.0c09860 |
| Kurzbeschreibung (Abstract): | The atomic structure of the Si-O-C tetrahedral network of an amorphous silicon oxycarbide polymer-derived ceramic (PDC) of the composition SiO0.94 +/- 0.11 C-1.13 +/- 0.08 was studied at both the short range and the intermediate range using 1D and 2D Si-29 nuclear magnetic resonance (NMR) spectroscopic techniques, respectively . The 1D Si-29 magic angle-spinning NMR spectrum of the PDC indicates that the Si-O-C network consists of SiO4, SiO3C, SiO2C2, and SiC4 units with relative abundances of approximately 26, 25, 20, and 29%, respectively. The 2D Si-29 extended CSA amplification spectrum of this PDC shows that the chemical shift anisotropy (Delta) of the mixed-bond SiOxC4-x units is significantly higher than that of the SiO4 units. On the other hand, the unusually high Delta-value for the SiC4 units was interpreted to be indicative of its role as the connecting element between the Si-O-C network and the free-carbon nanodomains. The 2D Si-29 double-quantum correlation NMR spectrum of this PDC indicates that there is extensive direct linking between SiO4 and SiO3C units in the Si-O-C network besides the connectivity between like SiOxC4-x units, while the SiO4 and SiO2C2 units are only linked via a SiO3C unit. In contrast, the SiO3C units show no restriction in linking with the other SiOxC4-x units in the network. Finally, the SiC4 units show significant clustering, which is consistent with their spatial localization at the interface between the Si-O-C network and the sp(2) C nanodomains. Such a spatial distribution of the SiOxC4-x units is argued to be consistent with their mass-fractal dimensions measured in previous studies. |
| Zusätzliche Informationen: | National Science Foundation (NSF), Gran Tnumbers NSF DMR-1855176; NSF DMR-1644779, State of Florida |
| Fachbereich(e)/-gebiet(e): | 11 Fachbereich Material- und Geowissenschaften 11 Fachbereich Material- und Geowissenschaften > Materialwissenschaft 11 Fachbereich Material- und Geowissenschaften > Materialwissenschaft > Fachgebiet Disperse Feststoffe |
| Hinterlegungsdatum: | 10 Mai 2021 06:27 |
| Letzte Änderung: | 10 Mai 2021 06:27 |
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