Electrical conductivity of tungsten doped vanadium dioxide obtained by the sol–gel technique

Abstract Thin films of tungsten-doped and pure vanadium dioxide with a metal–insulator transition are prepared by a sol–gel method. The films are characterized by X-ray diffraction, and electrical conductivity is measured in a temperature range from 50 to 380 K. It is shown that the conductivity of the films varies with temperature as σ ~ exp(aT − b / T). The experimental results are discussed from the viewpoint of the small polaron hopping conduction theory taking into account the influence of thermal lattice vibrations onto the resonance integral. The values of the activation energy and polaron radius are found. It is shown that doping with tungsten affects severely onto the electrical properties of vanadium dioxide.