Universal Features of the Electron Transport in Tungsten–Carbon Nanocomposites

The wide-temperature-range (4.2–300 K) electron transport had being studied in tungsten–carbon nanocomposites in tungsten concentration interval 0.1–0.45. It is shown that electron transport in the nanocomposites possesses the features of the universality, manifested in the form of power-law dependences of the conductivity on temperature in the two characteristic temperature intervals. The critical temperature separating the intervals is about 25–30 K and has no appreciable dependence on the value of tungsten concentration in nanocomposites. The power exponents of the temperature dependences of the conductivity in both temperature intervals are the non-monotonic functions of the tungsten concentration and vary in the range 0–2 with a wide minimum at 0.2 and 0.25 of tungsten content in the high- and low-temperature intervals, respectively. The observed power-law temperature corrections to the conductivity are simulated and discussed within the effective medium approximation in the framework of the model of the inelastic tunneling of the electrons between the conducting clusters in the tungsten–carbon nanocomposites.