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Phase separation of a hafnium alkoxide-modified polysilazane upon polymer-to-ceramic transformation-A case study

Ionescu, E. and Papendorf, B. and Kleebe, H.-J. and Breitzke, H. and Nonnenmacher, K. and Buntkowsky, G. and Riedel, R. (2012):
Phase separation of a hafnium alkoxide-modified polysilazane upon polymer-to-ceramic transformation-A case study.
In: Journal of the European Ceramic Society, 32 (9), pp. 1873-1881, [Online-Edition: http://apps.webofknowledge.com/full_record.do?product=WOS&se...],
[Article]

Abstract

The polymer-to-ceramic transformation of a hafnium alkoxide-modified polysilazane was investigated via thermogravimetric analysis coupled with in situ mass spectrometry (TG/MS), nuclear magnetic resonance (MAS NMR) and transmission electron microscopy (TEM). The results indicate that the structural evolution of the polysilazane upon ceramization is strongly affected by the modification with hafnium alkoxide. Thus, the content of carbon in the ceramic backbone was relatively low, whereas a large amount of SiN4 sites and a segregated carbon phase was present in the sample. Furthermore, this study revealed the formation of a SiHfCNO amorphous single phase ceramic via pyrolysis of the polymer at 700 degrees C whereas at higher pyrolysis temperatures precipitation of hafnia was observed, leading to an amorphous hafnia/silicon carbonitride ceramic nanocomposite. The precipitation of hafnia was shown to not rely on decomposition processes, but to be a result of rearrangement reactions occurring within the ceramic material. (C) 2011 Elsevier Ltd. All rights reserved.

Item Type: Article
Erschienen: 2012
Creators: Ionescu, E. and Papendorf, B. and Kleebe, H.-J. and Breitzke, H. and Nonnenmacher, K. and Buntkowsky, G. and Riedel, R.
Title: Phase separation of a hafnium alkoxide-modified polysilazane upon polymer-to-ceramic transformation-A case study
Language: English
Abstract:

The polymer-to-ceramic transformation of a hafnium alkoxide-modified polysilazane was investigated via thermogravimetric analysis coupled with in situ mass spectrometry (TG/MS), nuclear magnetic resonance (MAS NMR) and transmission electron microscopy (TEM). The results indicate that the structural evolution of the polysilazane upon ceramization is strongly affected by the modification with hafnium alkoxide. Thus, the content of carbon in the ceramic backbone was relatively low, whereas a large amount of SiN4 sites and a segregated carbon phase was present in the sample. Furthermore, this study revealed the formation of a SiHfCNO amorphous single phase ceramic via pyrolysis of the polymer at 700 degrees C whereas at higher pyrolysis temperatures precipitation of hafnia was observed, leading to an amorphous hafnia/silicon carbonitride ceramic nanocomposite. The precipitation of hafnia was shown to not rely on decomposition processes, but to be a result of rearrangement reactions occurring within the ceramic material. (C) 2011 Elsevier Ltd. All rights reserved.

Journal or Publication Title: Journal of the European Ceramic Society
Volume: 32
Number: 9
Uncontrolled Keywords: precursors polymer-derived ceramics (pdcs) nanocomposites transition metal oxides c-n ceramics solid-state nmr amorphous-silicon carbonitride molecular-dynamics atomic-structure x-ray crystallization precursors microstructure diffraction
Divisions: 07 Department of Chemistry
07 Department of Chemistry > Physical Chemistry
Date Deposited: 27 Oct 2014 20:43
Official URL: http://apps.webofknowledge.com/full_record.do?product=WOS&se...
Additional Information:

Sp. Iss. SI 936YP Times Cited:5 Cited References Count:35

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