## At the percolation threshold a small amount of CuS

Table 1.

pc, σc and slopes of the different regimes for the copper oxide samples.Samplepc/sσc/SPercolation regime/slopePercolation and SB 216763 regime/slopeDiffusion regime/slopeCuO16821.10 × 10−41.27Different slopes0.57Cu4O317883.10 × 10−4None0.890.55Cu2O21725.47 × 10−4None0.740.48Full-size tableTable optionsView in workspaceDownload as CSV

4.3. Numerical simulations

The results of the numerical simulations are shown in Fig. 10, where the electron mobility μe is plotted versus p in a half-logarithmic way. It can be recognized from the data that μe (pc) at the critical concentration appears quite clearly in the middle between the maximum and the minimum value of μe. Moreover the electron mobility μe depends strongly on the density of CuS–CuS-bonds and therefore on p, so that the curve shows a strong similarity to the experimental data in Fig. 5, Fig. 6 and Fig. 7. Therefore we believe that the CuS concentration increases approximately linearly with the measurement time t and the critical concentration pc is proportional to tc. As mentioned above σ − σc has been plotted in the analysis of the experimental data. Thereby σc accounts for the inevitable base conductance e.g. bulk conductance. For the numerical data it would be more appropriate to plot σ (or μe respectively) versus p − pc.