Electrical properties of WO3 powders

The electrical properties of WO₃ powders have been investigated. For a “fresh” sample, at low electric fields, the ln I vs $\text{T}{}^{\mathrm{<mtext>?</mtext><mtext>1</mtext><mtext>7</mtext>}}$ in the temperature range 60–360 K is consistent with a hopping mechanism. At higher fields the experimental results are explained in terms of a single centre Poole-Frenkel effect. The negative resistance regime and the switching processes can be due to a thermal mechanism.