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Single-Source-Precursor Synthesis of Hafnium-Containing Ultrahigh-Temperature Ceramic Nanocomposites (UHTC-NCs)

Yuan, Jia and Hapis, Stefania and Breitzke, Hergen and Xu, Yeping and Fasel, Claudia and Kleebe, Hans-Joachim and Buntkowsky, Gerd and Riedel, Ralf and Ionescu, Emanuel (2014):
Single-Source-Precursor Synthesis of Hafnium-Containing Ultrahigh-Temperature Ceramic Nanocomposites (UHTC-NCs).
In: Inorganic Chemistry, ACS Publications, pp. 10443-10455, 53, (19), ISSN 0020-1669,
[Online-Edition: http://dx.doi.org/10.1021/ic501512p],
[Article]

Abstract

Amorphous SiHfBCN ceramics were prepared from a commercial polysilazane (HTT 1800, AZ-EM), which was modified upon reactions with Hf(NEt2)4 and BH3·SMe2, and subsequently cross-linked and pyrolyzed. The prepared materials were investigated with respect to their chemical and phase composition, by means of spectroscopy techniques (Fourier transform infrared (FTIR), Raman, magic-angle spinning nuclear magnetic resonance (MAS NMR)), as well as X-ray diffraction (XRD) and transmission electron microscopy (TEM). Annealing experiments of the SiHfBCN samples in an inert gas atmosphere (Ar, N2) at temperatures in the range of 1300–1700 °C showed the conversion of the amorphous materials into nanostructured UHTC-NCs. Depending on the annealing atmosphere, HfC/HfB2/SiC (annealing in argon) and HfN/Si3N4/SiBCN (annealing in nitrogen) nanocomposites were obtained. The results emphasize that the conversion of the single-phase SiHfBCN into UHTC-NCs is thermodynamically controlled, thus allowing for a knowledge-based preparative path toward nanostructured ultrahigh-temperature stable materials with adjusted compositions.

Item Type: Article
Erschienen: 2014
Creators: Yuan, Jia and Hapis, Stefania and Breitzke, Hergen and Xu, Yeping and Fasel, Claudia and Kleebe, Hans-Joachim and Buntkowsky, Gerd and Riedel, Ralf and Ionescu, Emanuel
Title: Single-Source-Precursor Synthesis of Hafnium-Containing Ultrahigh-Temperature Ceramic Nanocomposites (UHTC-NCs)
Language: English
Abstract:

Amorphous SiHfBCN ceramics were prepared from a commercial polysilazane (HTT 1800, AZ-EM), which was modified upon reactions with Hf(NEt2)4 and BH3·SMe2, and subsequently cross-linked and pyrolyzed. The prepared materials were investigated with respect to their chemical and phase composition, by means of spectroscopy techniques (Fourier transform infrared (FTIR), Raman, magic-angle spinning nuclear magnetic resonance (MAS NMR)), as well as X-ray diffraction (XRD) and transmission electron microscopy (TEM). Annealing experiments of the SiHfBCN samples in an inert gas atmosphere (Ar, N2) at temperatures in the range of 1300–1700 °C showed the conversion of the amorphous materials into nanostructured UHTC-NCs. Depending on the annealing atmosphere, HfC/HfB2/SiC (annealing in argon) and HfN/Si3N4/SiBCN (annealing in nitrogen) nanocomposites were obtained. The results emphasize that the conversion of the single-phase SiHfBCN into UHTC-NCs is thermodynamically controlled, thus allowing for a knowledge-based preparative path toward nanostructured ultrahigh-temperature stable materials with adjusted compositions.

Journal or Publication Title: Inorganic Chemistry
Volume: 53
Number: 19
Publisher: ACS Publications
Divisions: 11 Department of Materials and Earth Sciences > Material Science > Dispersive Solids
11 Department of Materials and Earth Sciences > Material Science
11 Department of Materials and Earth Sciences
Date Deposited: 06 Nov 2014 13:27
Official URL: http://dx.doi.org/10.1021/ic501512p
Identification Number: doi:10.1021/ic501512p
Funders: .Y. acknowledges fi nancial support from China Scholarship Council (CSC) during his stay at TU Darmstadt., Furthermore, fi nancial support from the European Research Agency (FP7 FUNEA  Functional Nitrides for Energy Applications) and the Deutsche Forschungsgemeinschaft (DFG, No. SFB595) is gratefully acknowledged.
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