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@ARTICLE{Wen:186620,
author = {Wen, Qingbo and Xu, Yeping and Xu, Binbin and Fasel,
Claudia and Guillon, Olivier and Buntkowsky, Gerd and Yu,
Zhaoju and Riedel, Ralf and Ionescu, Emanuel},
title = {{S}ingle-source-precursor synthesis of dense
{S}i{C}/{H}f{C}$_{x}${N}$_{1-x}$-based ultrahigh-temperature
ceramic nanocomposites},
journal = {Nanoscale},
volume = {6},
number = {22},
issn = {2040-3372},
address = {Cambridge},
publisher = {RSC Publ.},
reportid = {FZJ-2015-00693},
pages = {13678 - 13689},
year = {2014},
abstract = {A novel single-source precursor was synthesized by the
reaction of an allyl hydrido polycarbosilane (SMP10) and
tetrakis(dimethylamido)hafnium(IV) (TDMAH) for the purpose
of preparing dense monolithic SiC/HfCxN1−x-based ultrahigh
temperature ceramic nanocomposites. The materials obtained
at different stages of the synthesis process were
characterized via Fourier transform infrared (FT-IR) as well
as nuclear magnetic resonance (NMR) spectroscopy. The
polymer-to-ceramic transformation was investigated by means
of MAS NMR and FT-IR spectroscopy as well as
thermogravimetric analysis (TGA) coupled with in situ mass
spectrometry. Moreover, the microstructural evolution of the
synthesized SiHfCN-based ceramics annealed at different
temperatures ranging from 1300 °C to 1800 °C was
characterized by elemental analysis, X-ray diffraction,
Raman spectroscopy and transmission electron microscopy
(TEM). Based on its high temperature behavior, the amorphous
SiHfCN-based ceramic powder was used to prepare monolithic
SiC/HfCxN1−x-based nanocomposites using the spark plasma
sintering (SPS) technique. The results showed that dense
monolithic SiC/HfCxN1−x-based nanocomposites with low open
porosity (0.74 $vol\%)$ can be prepared successfully from
single-source precursors. The average grain size of both
HfC0.83N0.17 and SiC phases was found to be less than 100 nm
after SPS processing owing to a unique microstructure:
HfC0.83N0.17 grains were embedded homogeneously in a β-SiC
matrix and encapsulated by in situ formed carbon layers
which acted as a diffusion barrier to suppress grain growth.
The segregated Hf-carbonitride grains significantly
influenced the electrical conductivity of the SPS processed
monolithic samples. While Hf-free polymer-derived SiC showed
an electrical conductivity of ca. 1.8 S cm−1, the
electrical conductivity of the Hf-containing material was
analyzed to be ca. 136.2 S cm−1.},
cin = {IEK-1},
ddc = {600},
cid = {I:(DE-Juel1)IEK-1-20101013},
pnm = {899 - ohne Topic (POF2-899)},
pid = {G:(DE-HGF)POF2-899},
typ = {PUB:(DE-HGF)16},
UT = {WOS:000344836800049},
doi = {10.1039/C4NR03376K},
url = {https://juser.fz-juelich.de/record/186620},
}