Kleebe, Hans-Joachim ; Nonnenmacher, Katharina ; Ionescu, Emanuel ; Riedel, Ralf ; Soraru, G. D. (2012)
Decomposition-Coarsening Model of SiOC/HfO2 Ceramic Nanocomposites Upon Isothermal Anneal at 1300°C.
In: Journal of the American Ceramic Society, 95 (7)
doi: 10.1111/j.1551-2916.2012.05227.x
Artikel, Bibliographie
Kurzbeschreibung (Abstract)
Pronounced variations of the crystallite size of hafnia (HfO2) precipitates in silicon oxycarbide (SiOC)–HfO2 ceramic nanocomposites were studied by TEM upon annealing bulk samples at 1300°C for times ranging from 1 to 200 h. TEM investigations revealed homogeneous nucleation and crystallization of hafnia in the amorphous, Hf-bearing SiOC matrix upon pyrolysis at 1300°C. Unexpectedly, high-temperature anneal resulted in a pronounced coarsening of the hafnia crystallites at internal surfaces, due to a decrease of the C content at surface-near regions. Based on the crystallite size, the diffusion coefficient of Hf was calculated via the Lifshitz-Slyozov-Wagner (LSW) theory for Ostwald ripening for both the bulk and internal surface regions. The diffusion coefficient of hafnium, DHf, in the C-depleted surface areas was 10−18 m2/s, whereas DHf of the SiOC bulk was three orders of magnitude lower with 10−21 m²/s. The present work underlines that the polymer-derived ceramics are in fact prone to phase separation and local chemical changes upon high-temperature treatment and are not as stable as commonly considered.
| Typ des Eintrags: | Artikel |
|---|---|
| Erschienen: | 2012 |
| Autor(en): | Kleebe, Hans-Joachim ; Nonnenmacher, Katharina ; Ionescu, Emanuel ; Riedel, Ralf ; Soraru, G. D. |
| Art des Eintrags: | Bibliographie |
| Titel: | Decomposition-Coarsening Model of SiOC/HfO2 Ceramic Nanocomposites Upon Isothermal Anneal at 1300°C |
| Sprache: | Englisch |
| Publikationsjahr: | Juli 2012 |
| Verlag: | Wiley |
| Titel der Zeitschrift, Zeitung oder Schriftenreihe: | Journal of the American Ceramic Society |
| Jahrgang/Volume einer Zeitschrift: | 95 |
| (Heft-)Nummer: | 7 |
| DOI: | 10.1111/j.1551-2916.2012.05227.x |
| URL / URN: | https://ceramics.onlinelibrary.wiley.com/doi/10.1111/j.1551-... |
| Kurzbeschreibung (Abstract): | Pronounced variations of the crystallite size of hafnia (HfO2) precipitates in silicon oxycarbide (SiOC)–HfO2 ceramic nanocomposites were studied by TEM upon annealing bulk samples at 1300°C for times ranging from 1 to 200 h. TEM investigations revealed homogeneous nucleation and crystallization of hafnia in the amorphous, Hf-bearing SiOC matrix upon pyrolysis at 1300°C. Unexpectedly, high-temperature anneal resulted in a pronounced coarsening of the hafnia crystallites at internal surfaces, due to a decrease of the C content at surface-near regions. Based on the crystallite size, the diffusion coefficient of Hf was calculated via the Lifshitz-Slyozov-Wagner (LSW) theory for Ostwald ripening for both the bulk and internal surface regions. The diffusion coefficient of hafnium, DHf, in the C-depleted surface areas was 10−18 m2/s, whereas DHf of the SiOC bulk was three orders of magnitude lower with 10−21 m²/s. The present work underlines that the polymer-derived ceramics are in fact prone to phase separation and local chemical changes upon high-temperature treatment and are not as stable as commonly considered. |
| Fachbereich(e)/-gebiet(e): | 11 Fachbereich Material- und Geowissenschaften 11 Fachbereich Material- und Geowissenschaften > Geowissenschaften 11 Fachbereich Material- und Geowissenschaften > Geowissenschaften > Fachgebiet Geomaterialwissenschaft 11 Fachbereich Material- und Geowissenschaften > Materialwissenschaft 11 Fachbereich Material- und Geowissenschaften > Materialwissenschaft > Fachgebiet Disperse Feststoffe |
| Hinterlegungsdatum: | 21 Mär 2013 09:00 |
| Letzte Änderung: | 19 Aug 2021 08:28 |
| PPN: | |
| Sponsoren: | The research was funded by the Deutsche Forschungsgemeinschaft (DFG) (Priority Program SPP 1181), and by the Ministry of Higher Education, Research and Arts in Hesse, Germany (Excellence Center AdRIA: Adaptronik – Research, Innovation, Application). |
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