Phase transformation, oxidation stability, and electrical conductivity of TiO₂-polysiloxane derived ceramics

There have been increasing needs for high-thermal stability and high-electrical conductivity materials. In this study, we in situ synthesized silicon oxycarbide (SiOC)–TiC _x O _y composites based on the pyrolysis of polysiloxane and carbothermal reaction between TiO₂ nanoparticles and free carbon in SiOC. The TiO₂ to TiC _x O _y conversion is dependent on the pyrolysis temperature. Higher pyrolysis temperature leads to more TiC formation but lower thermal stability. With more homogeneous distribution of TiO₂, the thermal stability of the SiOC–TiC _x O _y composite increases. This family of SiOC composite also demonstrates high electrical conductivity. The highest electrical conductivity is 5.03 S cm⁻¹ at 400 °C measurement temperature, the highest for air atmosphere condition. The key issue for tuning the SiOC–TiC _x O _y system for both thermal stability and electrical conductivity is to avoid the destabilization of the SiOC system.