Effect of density fluctuations on the physical properties of a disordered carbon

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Abstract
A number of properties, chemical composition, density, isothermal transport coefficients, paramagnetic susceptibility, and specific heat, of an anthracene char are investigated during the carbonization process. A simple physical picture for the carbonization process which assumes the existence of density fluctuations is proposed to explain these results. The nonmetal–metal transition which occurs under heat treatment is then interpreted as a percolation process as in Cohen and Jortner’s model. The low‐temperature specific heat results are also explained within this picture. Finally, it is shown that the inhomogeneous model proposed for the carbonization of anthracene char is supported by the recent work of Toulouse and Pfeuty who extend the phase transition phenomenology to the critical phenomena observed in the disordered solids.