Tungsten trioxide crystal is a material with electrical transport properties, which can be prepared by vapor phase transport and annealed under varying conditions. Well, do you know what the effects of oxygen-deficiency on electrical transport properties of tungsten trioxide crystals are?
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According to the experts, the jump in resistivity at the monoclinic-triclinic transition is due mainly to a decrease in electron mobility. The change at the triclinic transition is almost entirely the result of a large decrease in the carrier concentration. Changes in thermoelectric power cannot be explained on the basis of the ordinary electronic component; a lattice contribution must be present. Removal of oxygen pushes the transitions to lower temperatures, increases the carrier concentration, decreases the Hall mobility, and changes the sign of its temperature dependence. It is believed that the basic defect unit is not the oxygen vacancy but the Anderson-Hyde disk of shear. The increase of mobility with increasing temperature is attributed to hopping of charge carriers in place of band processes in the defect regions. Decreases in the optical phonon drag and transport energy terms are needed to fit the thermoelectric power behavior of the monoclinic phase. For stoichiometric tungsten trioxide, the results are in general agreement with previous reports.
