Complex impedance study on polymer-derived amorphous silicon carbonitride

Polymer-derived amorphous-SiCN pyrolyzed at 1200 °C was studied by impedance spectroscopy at different frequencies and temperatures. Obtained impedance spectra were analyzed by using equivalent circuit method. Results revealed that two relaxation effects were involved over the entire studied temperature range, which corresponded to free carbon phase at high frequency and the interface at low frequency. The impedance spectroscopy could be well-fitted by two parallel RC circuits in series. Interface behavior dominated the polarization relaxation process, which was controlled by the resistance as well as the capacitance of interface. All processes performed a 1/T^1/4 behavior, which follows a three-dimensional (3D) random hopping mechanism. This paper further found that amorphous-SiCN ceramic materials underwent an interfacial charge polarization process over a frequency range from 0.05 Hz to 10 MHz at different temperatures from −50 to 300 °C.