Electrical conductivity of dense, bulk silicon-oxycarbide ceramics

The effects of sintering temperature on the electrical conductivity of dense, bulk SiOC ceramics were investigated in polysiloxane-derived SiOC ceramics prepared by a conventional ceramic processing route. The electrical conductivity of the SiOC ceramics increased with increasing sintering temperature between 1450 °C and 1650 °C. Raman spectroscopy and high-resolution transmission electron microscopy revealed that the SiOC ceramics contained graphitic species (nanocrystalline graphite/turbostratic carbon) and nano-crystalline SiC grains that were precipitated during the fabrication process. The increase in the electrical conductivity is attributable to an increase in the sp2 carbon bonding portion within a carbon cluster as the sintering temperature increases. The SiOC ceramics sintered at 1650 °C exhibited an electrical conductivity as high as 7 Ω−1 cm−1 at room temperature. The electrical conductivity of SiOC ceramics sintered at 1550 °C was ∼1.0 Ω−1 cm−1 at 4 K and ∼2.0 Ω−1 cm−1 at 300 K.