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Si OCN ceramics are formed by the thermal decomposition of a polyvinylsilazane precursor in the presence of a dicumyl peroxide ( DP) thermal initiator with different concentrations. The Si OCN ceramics pyrolyzed at 1000°C with different concentrations of DP are characterized with X-ray diffraction, transmission electron microscope, electron paramagnetic resonance, and UV-visible spectroscopy. We find that the structure and optical band gap of the Si OCN ceramics can be changed by altering the concentration of DP. There is a critical concentration, at which the structural and optical behavior varied in different ways as a function of the concentration of DP. The detailed mechanism is discussed. [ABSTRACT FROM AUTHOR]

The polyyttriocarbosilane (PYCS) with various quantities of yttrium was obtained by reacting yttrium acetylacetonate (Y(AcAc)) with polycarbosilane (PCS). The molecular weight, softening point, and Si-H bond content of the resulting PYCS are controlled by the Y(AcAc):PCS weight ratio, reaction temperature and reaction time. The main chain of the PYCS is made up of alternating carbon and silicon atoms with small amount of Si-O-Y presented in the main chain and Si-H groups at the side chain. The pyrolysis process of PYCS was investigated by TG and XRD. The results reveal that the polymer-to-ceramic transition of the PYCS occurs in three steps. The final ceramics obtained at 1,800 °C contain a large number of β-SiC crystallites and a small amount of α-SiC crystallites. [ABSTRACT FROM AUTHOR]

This paper presents a passive wireless polymer-derived silicon carbonitride (SiCN) ceramic sensor based on cavity radio frequency resonator together with integrated slot antenna. The effect of the cavity sensor dimensions on the Q-factor and resonant frequency is investigated by numerical simulation. A sensor with optimal dimensions is designed and fabricated. It is demonstrated that the sensor signal can be wirelessly detected at distances up to 20 mm. Given the high-temperature stability of the SiCN, the sensor is very promising for high-temperature wireless sensing applications. [ABSTRACT FROM AUTHOR]