Effects of different polymer precursors on the characteristics of SiOC bulk ceramics

Silicon oxycarbide (SiOC) is a material with a number of advantageous properties that strongly depend on its structure. In this study, bulk SiOC ceramics are prepared from polymer precursors with different side groups (Si-H, Si-CH3, Si-CH=CH2, and Si-C6H5) to understand the influence of the C content and network on the structures and properties of the resulting SiOC ceramics. The influence of the side groups on the thermophysical characteristics, phase evolution, oxidation resistance, and electrical conductivity of the SiOC materials is systematically studied. The SiOC samples show superior thermal stability in the air atmosphere up to 690-860 degrees C. The highest electrical conductivity is 705.3Sm(-1) at 403 degrees C, the highest to date for this family of materials and 3.5 times that of other reported studies. A new concept of free C connectivity is created to correlate with the electrical conductivity. This new conducting behavior with high thermal stability presents promising application potentials in high-temperature semi-conducting components.