Electrical conductivity of α-H _x V₂O₅ (X=0.00-0.27): Dependence of hydrogen concentration and orientation

Abstract

The dependence of the electrical conductivity, σ, on the hydrogen concentration and crystallographic orientation has been investigated using single crystals of H_xV₂O₅, which were grown by the Bridgeman method and doped with hydrogen within the solid solubility in the α phase by the spillover technique. The temperature dependence of σ showed the feature of diffusive hopping of thermally activated electrons above ∼180 K and variable range hopping below ∼180 K. The dependence of σ on the crystallographic orientation was little different from that of V₂O₅. The change in σ with the hydrogen concentration was not monotonic; σ increases withx up tox }-0.06, but decreases abovex }-0.06. This behaviour can be explained based on the competition between the increase in the carrier density and the depression of the mobility of carriers with increasingx.