Mechanisms for the generation of thermopower carbon-graphite materials with different crystal structures

The results of experimental and theoretical studies of the temperature depe ndence of the thermopower of carbon-graphite materials with different cryst al structures are presented. It is shown that the mechanisms giving rise to the thermopower in these materials are different. In coarse-grained graphi tes the main contribution to the total thermopower at low temperatures deri ves from the phonon-drag effect on the charge carriers, while the contribut ion of the diffusion component of the thermopower at these temperatures is insignificant. In a fine-grained graphite the main contribution to the tota l thermopower in the entire temperature interval is from the diffusion comp onent of the thermopower, while the contribution of the phonon component is small even at low temperatures. (C) 2001 American Institute of Physics.