Please use this identifier to cite or link to this item: doi:10.22028/D291-24641
Title: A solid state 29Si and 13C NMR study on the synthesis of thin silicon-oxycarbide glass sheets by a sol-gel route
Author(s): Suyal, Navin
Hoebbel, Dagobert
Mennig, Martin
Schmidt, Helmut K.
Language: English
Year of Publication: 1999
OPUS Source: Journal of materials chemistry. - 9. 1999, 12, S. 3061-3067
SWD key words: Fester Zustand
Biochemische Analyse
Chemische Analyse
DDC notations: 540 Chemistry
Publikation type: Journal Article
Abstract: 29Si and 13C MAS NMR spectroscopy, DTA-TG and elemental analysis were used to study the evolution of metastable oxycarbide phases starting from thin gel sheets derived from methyltriethoxysilane (MTEOS), tetraethoxysilane (TEOS) and a colloidal silica containing sol, up to 1450°C under a nitrogen atmosphere. The stoichiometric formulae of the glasses obtained by the semi-quantitative analysis of 29Si MAS NMR spectra were found to be in good agreement with those obtained by chemical analysis. It was found that the addition of colloidal silica sol delays the decomposition of methyl groups in MTEOS containing condensates. This delayed decomposition of the methyl groups was attributed to facilitate the strengthening of the matrix, thus leading to crack free sintering of sheets up to 400°C in air and for T>900°C under nitrogen. A significant portion (>40%) of the total carbon present in the glasses was found to exist as free carbon. 13C NMR showed that unsaturated C=C bonds exist in gels heat treated at 1000 °C, but they disappear in heat treated gels at 1200 and 1450°C. Both 29Si and 13C NMR spectra indicate the formation of a ca. 15 atom% SiC phase in the glass sheets sintered at 1450°C, which were found to be amorphous up to 1200°C.
Link to this record: urn:nbn:de:bsz:291-scidok-29563
Date of registration: 1-Sep-2010
Faculty: SE - Sonstige Einrichtungen
Department: SE - INM Leibniz-Institut für Neue Materialien
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