Impact of Crystallinity on Relationship Between Electrical and Thermal Conductivities in Bulk Graphitic Materials

Highly conductive graphitic materials are of interest in a wide range of industrial applications. The direct measurement of high thermal conductivity values is difficult due to issues with inhomogeneity and thermal response acquisition. Electrical conductivity on the other hand can be conveniently and accurately measured. Based on theory and experimental measurements on graphene it is evident that both quantities depend on the crystalline perfection of the material. This communication provides a robust correlation between thermal and electrical conductivity, for bulk graphitic materials that have chemically bonded structures. The relationship covers a very wide range of materials with varying degrees of crystallinity. Given the high material variability a reasonable correlation is found with a 0.91 coefficient of determination and a 95% confidence interval of 7.5%, which is suitable for the quick estimation of thermal conductivity. It was further found that variations in the correlation are discernible between measurements in-plane and across plane, with isotropic materials falling halfway between the two. With further development this approach can be used to provide a rapid and indirect measurement of high thermal conductivity values.