## 2 Results and Discussion
[PERSON] and [PERSON] reported on the conduction behavior of SiCN/C (\(\phi_{\rm C}\) = 5 vol.%) and SiO/C (\(\phi_{\rm C}\) = 12 vol.%) prepared at T = 1500 \({}^{\circ}\)C and T = 1300 \({}^{\circ}\)C, respectively [36; 66]. Both authors interpreted their data considering the variable range hopping model (VRH) postulated by [PERSON] and [PERSON] [67; 68]. [PERSON] et al. showed furthermore that the conduction occurs by phonon-assisted hopping near the Fermi-energy and not near the mobility edges [36]. [PERSON] estimated the density of states near the Fermi energy to be N = \(10^{17}\) - \(10^{19}\) eV\({}^{-1}\) cm\({}^{3}\), by assuming a localization length of \(\alpha^{-1}\) = 10 A, which is typical for amorphous semiconductors [66]. Based on the correlation between the parameters \(\sigma_{0}\) and T\({}_{0}\) in the general equation for transport in localized states (i.e., \(\sigma=\sigma_{0}\)[\(-\left(\frac{T_{0}}{T}\right)^{1/\beta}\)], [PERSON] et al. investigated a SiCN/C system (\(\phi_{\rm C}\) = 22 vol.%) considering the nearest neighbor hopping, also called band tail hopping (BTH), as the main transport mechanism [63]. Figure 7 shows the Arrhenius plots for the electrical conductivity of three C-11 samples prepared at 1000 \({}^{\circ}\)C, 1400 \({}^{\circ}\)C and 1600 \({}^{\circ}\)C. A linear dependency of \(\sigma\) with T\({}^{-1}\) is evident for all samples, indicating an activated transport and activation energies E\({}_{\rm a}\) of 0.4 eV, 0.23 eV and 0.04 eV for the samples prepared at 1000 \({}^{\circ}\)C, 1400 \({}^{\circ}\)C and 1600 \({}^{\circ}\)C, respectively. For the sake of comparison, a SiCN/C system prepared at 1300 \({}^{\circ}\)C showed an E\({}_{\rm a}\) value of 0.15 eV [36] and was thus similar to the C-11 sample prepared at 1400 \({}^{\circ}\)C.  
Plotting the conductivity data against T\({}^{-1/\beta}\) (\(\beta\) = 3,4) yields no clear evidence of a non-Arrhenius behavior, underlining the presence of thermally activated transport in all the investigated samples. However, one cannot rule out that both VRH and thermally activated transport exist in this temperature range, thus further measurements are needed for an unambiguous mechanistic clarification. The decreasing activation energies with increasing the synthesis temperature indicate a continuous reduction of the band gap in the SiOC/C system and may be related to the evolution of the carbon phase with the temperature. Interestingly, the activation energy of the C-11 ceramic sample annealed at 1600 \({}^{\circ}\)C, i.e., 0.04 eV, was comparable to that of glassy carbon (0.03 eV [69]). Figure 8 shows the activation energy E\({}_{\rm a}\) as a function of the segregated carbon in the SiOC/C samples prepared at 1600 \({}^{\circ}\)C. Three different electrical transport regimes can be distinguished, with activation energies decreasing from ca. 1 eV in regime I to ca. 0.3 eV in regime II and further to ca. 0.03 eV in regime III. In regime I (Figure 8), conduction is considered to occur within the amorphous silica network, as the amount of sp\({}^{2}\) carbon is very low (\(\phi_{\rm C}\) < 1 vol.%) [70; 71]. According to [PERSON], high concentration of silicon dangling bonds is present within amorphous silica SiO\({}_{\rm x}\), showing a VRH transport within localized states [70; 71]. A VRH conduction mechanism is also likely for low-carbon SiOC/C materials. Figure 1:1 Electrical conductivity of C-11 as a function of the inverse of the treatment temperature. In regime II (\(\phi_{\rm C}\) = 2-6 vol.%, Figure 8), the sp\({}^{2}\)-hybridized carbon precipitations were still separated by the SiOC matrix but the resulting potential barrier for the transport was lowered (E\({}_{\rm a}\approx\) 0.3 eV) as compared to that of regime I. The low activation energy arose from additional carbon defects states within the band gap presumably overlapping with the silicon dangling bonds states.