Gumann, Sina ; Nestle, Nikolaus ; Liebau-Kunzmann, Verena ; Riedel, Ralf (2007):
Investigations of Li-containing SiCN(O) ceramics via 7Li MAS NMR.
In: Solid State Nuclear Magnetic Resonance, 31 (2), pp. 82-90. Elsevier, ISSN 09262040,
[Article]
Abstract
Lithium-containing silicon (oxy)carbonitride ceramics (SiCN(O):Li) were synthesized via precursor-to-ceramic-transformation of Li-containing (poly)silazanes. The precursors were obtained by lithiation of 2,4,6-trimethyl-2,4,6-trivinylcyclotrisilazane with n-butyllithium and by reaction of a commercial poly(organosilazane) VL20® with metallic lithium. The annealing treatment was carried out at temperatures between 200 and 1400 °C in argon (ΔT=200 °C) and yielded Li-containing silicon (oxy)carbonitride. X-ray powder diffraction revealed that the resulting SiCN(O):Li ceramics were basically amorphous up to temperatures of 1000 °C and formed LiSi2N3, graphite and silicon carbide as crystalline phases at higher temperatures. 7Li MAS NMR spectroscopy was carried out to investigate the structure of the Li-containing phases and to study the reaction path of metallic Li with polysilazane. Based on the NMR spectra, there is almost no difference found in the chemical shift of the SiCN(O):Li ceramics obtained at different temperatures. Accordingly, Li is assigned to be mainly coordinated to N and O present as contaminant element. Relaxation time measurements showed that the most mobile Li+ species seems to be present in the product obtained in the pyrolysis temperature range between 600 and 1000 °C.
| Item Type: | Article |
|---|---|
| Erschienen: | 2007 |
| Creators: | Gumann, Sina ; Nestle, Nikolaus ; Liebau-Kunzmann, Verena ; Riedel, Ralf |
| Title: | Investigations of Li-containing SiCN(O) ceramics via 7Li MAS NMR |
| Language: | English |
| Abstract: | Lithium-containing silicon (oxy)carbonitride ceramics (SiCN(O):Li) were synthesized via precursor-to-ceramic-transformation of Li-containing (poly)silazanes. The precursors were obtained by lithiation of 2,4,6-trimethyl-2,4,6-trivinylcyclotrisilazane with n-butyllithium and by reaction of a commercial poly(organosilazane) VL20® with metallic lithium. The annealing treatment was carried out at temperatures between 200 and 1400 °C in argon (ΔT=200 °C) and yielded Li-containing silicon (oxy)carbonitride. X-ray powder diffraction revealed that the resulting SiCN(O):Li ceramics were basically amorphous up to temperatures of 1000 °C and formed LiSi2N3, graphite and silicon carbide as crystalline phases at higher temperatures. 7Li MAS NMR spectroscopy was carried out to investigate the structure of the Li-containing phases and to study the reaction path of metallic Li with polysilazane. Based on the NMR spectra, there is almost no difference found in the chemical shift of the SiCN(O):Li ceramics obtained at different temperatures. Accordingly, Li is assigned to be mainly coordinated to N and O present as contaminant element. Relaxation time measurements showed that the most mobile Li+ species seems to be present in the product obtained in the pyrolysis temperature range between 600 and 1000 °C. |
| Journal or Publication Title: | Solid State Nuclear Magnetic Resonance |
| Journal volume: | 31 |
| Number: | 2 |
| Publisher: | Elsevier |
| Uncontrolled Keywords: | Silazanes, SiCN(O), 7Li MAS NMR spectroscopy |
| Divisions: | 11 Department of Materials and Earth Sciences 11 Department of Materials and Earth Sciences > Material Science 11 Department of Materials and Earth Sciences > Material Science > Dispersive Solids DFG-Collaborative Research Centres (incl. Transregio) DFG-Collaborative Research Centres (incl. Transregio) > Collaborative Research Centres 05 Department of Physics 05 Department of Physics > Institute of Applied Physics Zentrale Einrichtungen DFG-Collaborative Research Centres (incl. Transregio) > Collaborative Research Centres > CRC 595: Electrical fatigue DFG-Collaborative Research Centres (incl. Transregio) > Collaborative Research Centres > CRC 595: Electrical fatigue > A - Synthesis DFG-Collaborative Research Centres (incl. Transregio) > Collaborative Research Centres > CRC 595: Electrical fatigue > A - Synthesis > Subproject A4: Novel functional ceramics using anionic substitution in oxidic systems DFG-Collaborative Research Centres (incl. Transregio) > Collaborative Research Centres > CRC 595: Electrical fatigue > B - Characterisation DFG-Collaborative Research Centres (incl. Transregio) > Collaborative Research Centres > CRC 595: Electrical fatigue > B - Characterisation > Subproject B5: Model experiments about interactions between ferroelectric domains with point defects and their agglomerates |
| Date Deposited: | 17 Apr 2012 09:21 |
| Official URL: | http://dx.doi.org/10.1016/j.ssnmr.2007.02.003 |
| Additional Information: | SFB 505 Cooperation A4, B5 |
| Identification Number: | doi:10.1016/j.ssnmr.2007.02.003 |
| Funders: | For financial support we thank the German Science Foundation, SFB 595 “Electric Fatigue in Functional Materials”. |
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