TY - JOUR
T1 - Nanostructure and energetics of carbon-rich SiCN ceramics derived from polysilylcarbodiimides
T2 - Role of the nanodomain interfaces
AU - Widgeon, S.
AU - Mera, G.
AU - Gao, Y.
AU - Stoyanov, E.
AU - Sen, S.
AU - Navrotsky, A.
AU - Riedel, R.
N1 - Copyright:
Copyright 2012 Elsevier B.V., All rights reserved.
PY - 2012/3/27
Y1 - 2012/3/27
N2 - SiCN polymer-derived ceramics (PDCs) with different carbon contents have been synthesized by pyrolysis of poly(phenylvinylsilylcarbodiimide) and of poly(phenylsilsesquicarbodiimide), and their structure and energetics have been studied using 29Si, 13C, 15N, and 1H solid state nuclear magnetic resonance (NMR) spectroscopy and oxide melt solution calorimetry. The structure of these PDCs at lower carbon content (35-40 wt %) and pyrolysis temperatures (800 °C) consists primarily of amorphous nanodomains of sp 2 carbon and silicon nitride with an interfacial region characterized by mixed bonding between N, C, and Si atoms that is likely stabilized by the presence of hydrogen. The average size of the carbon domains increases with increasing carbon content, and a continuously connected amorphous carbon matrix is formed in PDCs with 55-60 wt % C. The interfacial silicon-carbon and nitrogen-carbon bonds are destroyed with concomitant hydrogen loss upon increasing the pyrolysis temperature to 1100 °C. Calorimetry results demonstrate that the mixed bonding between C, N, and Si atoms in the interfacial regions play a key role in the thermodynamic stabilization of these PDC. They become energetically less stable with increasing annealing temperature and concomitant decrease of mixed bonds and hydrogen loss.
AB - SiCN polymer-derived ceramics (PDCs) with different carbon contents have been synthesized by pyrolysis of poly(phenylvinylsilylcarbodiimide) and of poly(phenylsilsesquicarbodiimide), and their structure and energetics have been studied using 29Si, 13C, 15N, and 1H solid state nuclear magnetic resonance (NMR) spectroscopy and oxide melt solution calorimetry. The structure of these PDCs at lower carbon content (35-40 wt %) and pyrolysis temperatures (800 °C) consists primarily of amorphous nanodomains of sp 2 carbon and silicon nitride with an interfacial region characterized by mixed bonding between N, C, and Si atoms that is likely stabilized by the presence of hydrogen. The average size of the carbon domains increases with increasing carbon content, and a continuously connected amorphous carbon matrix is formed in PDCs with 55-60 wt % C. The interfacial silicon-carbon and nitrogen-carbon bonds are destroyed with concomitant hydrogen loss upon increasing the pyrolysis temperature to 1100 °C. Calorimetry results demonstrate that the mixed bonding between C, N, and Si atoms in the interfacial regions play a key role in the thermodynamic stabilization of these PDC. They become energetically less stable with increasing annealing temperature and concomitant decrease of mixed bonds and hydrogen loss.
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U2 - 10.1021/cm2038238
DO - 10.1021/cm2038238
M3 - Article
AN - SCOPUS:84859132978
SN - 0897-4756
VL - 24
SP - 1181
EP - 1191
JO - Chemistry of Materials
JF - Chemistry of Materials
IS - 6
ER -