The size effect in current-voltage characteristic of VO2-based ceramics in the on-state

Current-voltage characteristics of (wt.%) 45VO^sub 2^-15VPG-5Cu-35SnO^sub 2^ ceramics in the on-state were investigated in the electric current interval between 0.3 A and 5 A. Transition from the region with negative differential resistance to the region with positive differential resistance is observed in current-voltage characteristic when electric current increases. The reason of such behaviour is the limitation of lateral expansion for the filament of VO^sub 2^ metal phase by the sample's size. The change in the sign of differential resistance occurs, when the cross-section area of the filament reaches the sample's cross-section area. In this case the phase transition of VO^sub 2^ into metal state is completed in the whole volume of the sample. Therefore at further increasing of current the current-voltage characteristic has the positive differential resistance.[PUBLICATION ABSTRACT]