These changes in the structural features of chars can be quatified by means of structural ratios calculated from the Raman spectra of the chars. Values of \(\frac{ID}{IG}\) and \(\frac{IV}{ID}\)ratios as well as the Total Raman Area TRA are given in table 1.
One can observe that the ratio ID/IG significantly
increases with the pyrolysis temperature indicating the formation of condensed
aromatic ring structures having defects, which proportion is higher than the
graphitized structures. These D structures would be formed by the condensation
of small aromatic amorphous carbon structures (valley region), which
contribution to the Raman signal decreases significantly with pyrolysis
temperature increase. This feature is also reported in previous study [19]