Conductance in Nb6VSb3O25—a new ceramic compound

• The anomalous behaviour of conductance revealed its broad minimum.
• The non-linear I–V effect was recognized as the accumulation of induced charge.
• EF = 0.06 eV and TF = 731 K calculated from the diffusion component of thermopower are characteristic for insulators.

The electrical measurements performed on Nb6VSb3O25-ceramics showed a sharp increase of the n-type electrical conduction at 330 K from the extrinsic region with the activation energy of Ea = 0.01 eV to the intrinsic one with the activation energy of Ea = 0.75 eV. At high temperatures, i.e. above 520 K, a rather well defined linear slope of diffusion thermopower was found which extrapolates to (0, 0). The I–V characteristics, measured at 300 and 400 K, showed a symmetric and non-linear behaviour as well as a broad minimum of the conductance G vs. the applied voltage V, which is being shifted into the higher voltages and simultaneously its value falls with a rise in temperature. These results are interpreted in a framework of deep donor and shallow trap levels as of grain boundaries.

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