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 degrees C and 1650 degrees 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 sp(2) carbon bonding portion within a carbon cluster as the sintering temperature increases. The SiOC ceramics sintered at 1650 degrees C exhibited an electrical conductivity as high as 7 Omega(-1) cm(-1) at room temperature. The electrical conductivity of SiOC ceramics sintered at 1550 degrees C was similar to 0-1 Omega(-1) cm(-1) at 4K and similar to 2.0 Omega(-1) cm(-1) at 300 K. (C) 2014 Elsevier Ltd. All rights reserved.