ABSTRACT
A. Thermal Conductivity In electrical insulators heat is carried by phonons, while in pure metals heat is carried predominantly by the charge carriers. In semimetallic graphite the ther mal conductivity is due almost entirely to the lattice in the pristine material above the liquid helium temperature range because of the low carrier concen tration in graphite. Generally, in GICs the charge transfer leads to a large in crease in carrier concentration and consequently to the presence of a relatively large electronic contribution to the thermal conductivity. Thus, in certain tem perature ranges, the electronic thermal conductivity, ke, may be comparable to the lattice contribution, kl [51]. In that case the total thermal conductivity is expressed as
In all the GICs investigated so far, interpretation of the experimental data showed that the effect of intercalation is to decrease the total thermal conduc tivity at high temperature and to increase it at low temperature with respect to the pristine material [23,24,51]. Indeed, the lattice defects introduced by inter calation decrease the lattice thermal conductivity around and above the dielectric maximum. Also, the large increase in carrier concentration in GICs due to charge transfer adds a significant electronic contribution to the thermal conductivity, especially at low temperatures.
