2020 journal article

Electrical Conductivity and Structural Evolution of Polymer Derived SiC Ceramics Pyrolyzed From 1200°C to 1800°C

Journal of Micro and Nano-Manufacturing.

By: M. Chowdhury, K. Wang, Y. Jia & C. Xu

Source: Crossref
Added: June 6, 2020

Abstract <jats:p>Room temperature electrical conductivity and microstructure of polymer derived SiC pyrolyzed at temperatures ranging from 1200°-1800°C was studied. We have shown that both free carbon content and pyrolysis temperature have a significant effect on the DC conductivity of PDC SiC. The room temperature DC conductivity of the SiC increased gradually with increasing pyrolysis temperature, and it drastically increases 3 orders of magnitude after 1500°C. This Insulator-conductor transition occurs by the formation of a network of turbostratic carbon (percolative network). Below the percolation regime, hopping enables the electron movement from one carbon cluster site to another. Microstructural investigation with XRD, Raman, and TEM analysis showed that the crystal size of SiC increases with increasing pyrolysis temperature, and carbon clusters act as an inhibitor for grain growth at lower pyrolysis temperature. Upon dissociation of clusters, accelerated grain growth occurs and graphitization of carbon occurs along the grains.