期刊
INORGANIC CHEMISTRY
卷 53, 期 19, 页码 10443-10455出版社
AMER CHEMICAL SOC
DOI: 10.1021/ic501512p
关键词
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资金
- China Scholarship Council (CSC)
- European Research Agency (FP7 FUNEA-Functional Nitrides for Energy Applications)
- Deutsche Forschungsgemeinschaft (DFG) [SFB595]
Amorphous SiHfBCN ceramics were prepared from a commercial polysilazane (HTT 1800, AZ-EM), which was modified upon reactions with Hf(NEt2)(4) and BH3 center dot 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, N-2) at temperatures in the range of 1300-1700 degrees 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.
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