Abstract
Silicon oxycarbide samples were prepared by polymer pyrolysis using a methyltriethoxysilane-derived precursor. Transparent crack-free gel samples were obtained from the alkoxide by the sol–gel process. The dried gel samples were pyrolysed at different temperatures in the range between 400 and 1500
°C in Ar atmosphere. The chemical and microstructural evolution during pyrolysis were followed by FT-IR absorption, Raman scattering and photoluminescence (PL).
The FT-IR spectra show the change in Si–O–Si asymmetric stretching, C–H
x
, Si–CH
3 stretching vibrational bands. The peak position and shape of these bands were found stable up to 600
°C. Above this temperature, a remarkable change in shape and peak position of Si–O–Si related vibration, reduction in C–H
x
and Si–CH
3 stretching absorption bands have been observed. Degradation of Si–CH
3 and the simultaneous formation of Si–CH
2–Si via Si–CH
2–CH
2–Si is explicitly observed, experimentally. Annealing the sample at 800
°C starts to show the clear presence of D and G bands, related to the free carbon precipitation and its segregation with the temperature. The broad PL spectra centered at around 670
nm for the samples pyrolysed at 1500
°C shows an important information regarding the presence of crystalline SiC.