NONLINEAR ELECTRICAL-CONDUCTIVITY OF V2O5 SINGLE-CRYSTALS

The electrical conductivity of V2O5 was studied in the temperature range 200-300 K. The measured I-U characteristics in this range are S shaped, consisting of a linear, Ohmic regime at lower current densities and a nonlinear one at higher current densities. ln-sigma-vs-(10(3)/T) curves recorded in the Ohmic regime of the corresponding I-U characteristics show a temperature depended activation of the conductivity. In the negative-differential-resistance (NDR) region of the I-U characteristics, periodic, quasi-periodic, and chaotic oscillations were occasionally observed. A considerable increase of the sample temperature was registered in the NDR region of the I-U curves. It is shown that current filamentation can well explain qualitatively and quantitatively the form of the I-U curves. A purely thermal process can account both for the NDR region and for the temperature elevation in this region.