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B/C/N materials and B4C synthesized by a non-oxide sol-gel process

Völger, Karl-Wolfgang and Kroke, Edwin and Gervais, C. and Saito, T. and Babonneau, F. and Riedel, Ralf and Iwamoto, Y. and Hirayama, T. (2003):
B/C/N materials and B4C synthesized by a non-oxide sol-gel process.
In: Chemistry of materials, 15 (3), ACS Publications, pp. 755-764, [Article]

Abstract

B-trichloroborazene B3N3H3Cl3 reacts with bis(trimethylsilyl)carbodiimide Me3Si-NCNSiMe3 in THF or toluene, or without any solvent, to form non-oxide gels. The xerogels, amorphous B/C/N materials, and (semi)crystalline pyrolysis products were characterized using infrared (FTIR) and Raman spectroscopy, 11B- and 15N-nuclear magnetic resonance spectroscopy (NMR), X-ray powder diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and elemental analysis. In addition, the pyrolysis process was investigated through thermal gravimetry coupled with mass spectrometry (TG-MS). The xerogels consist of a three-dimensional polymeric network of borazene rings linked by carbodiimide groups. Interestingly, the sol-gel transition is phenomenologically analogous to oxide systems and the polymers are almost free of chlorine and trimethylsilyl endgroups. Pyrolysis at 1200 °C provides an amorphous ceramic with the composition BC0.23N1.1Si0.05H0.09 � B4CN4. This material starts to crystallize around 1600 °C under evolution of nitrogen, forming nearly pure B4C at 2000 °C. Very small amounts of amorphous carbon as well as carbon nanotubes were also present.

Item Type: Article
Erschienen: 2003
Creators: Völger, Karl-Wolfgang and Kroke, Edwin and Gervais, C. and Saito, T. and Babonneau, F. and Riedel, Ralf and Iwamoto, Y. and Hirayama, T.
Title: B/C/N materials and B4C synthesized by a non-oxide sol-gel process
Language: English
Abstract:

B-trichloroborazene B3N3H3Cl3 reacts with bis(trimethylsilyl)carbodiimide Me3Si-NCNSiMe3 in THF or toluene, or without any solvent, to form non-oxide gels. The xerogels, amorphous B/C/N materials, and (semi)crystalline pyrolysis products were characterized using infrared (FTIR) and Raman spectroscopy, 11B- and 15N-nuclear magnetic resonance spectroscopy (NMR), X-ray powder diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and elemental analysis. In addition, the pyrolysis process was investigated through thermal gravimetry coupled with mass spectrometry (TG-MS). The xerogels consist of a three-dimensional polymeric network of borazene rings linked by carbodiimide groups. Interestingly, the sol-gel transition is phenomenologically analogous to oxide systems and the polymers are almost free of chlorine and trimethylsilyl endgroups. Pyrolysis at 1200 °C provides an amorphous ceramic with the composition BC0.23N1.1Si0.05H0.09 � B4CN4. This material starts to crystallize around 1600 °C under evolution of nitrogen, forming nearly pure B4C at 2000 °C. Very small amounts of amorphous carbon as well as carbon nanotubes were also present.

Journal or Publication Title: Chemistry of materials
Volume: 15
Number: 3
Publisher: ACS Publications
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
Date Deposited: 19 Nov 2008 15:59
License: [undefiniert]
Funders: We gratefully acknowledge financial support from Deutsche Forschungsgemeinschaft (DFG, Bonn) through the project Kr1739/5-1 and the Fonds der Chemischen Industrie (FCI, Frankfurt). K.W.V. acknowledges a HSP III fellowship for Japan by the German Academic, Exchange Service (DAAD), Bonn, Germany. E.K. is grateful to F. Lange (University of California, Santa Barbara, CA) for his support and to the Alexander von Humboldt-Foundation (Bonn) for granting a Feodor Lynen Fellowship.
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