Negative Resistance, Conductive Switching and Memory Effect in α-Fe₂O₃ Ceramics (II)

Abstract

A series of phenomena have been encounted by implying negative resistance, conductive switching and memory switching effects in the sintered α-Fe₂O₃ with the conductive path formed by electrical breakdown. In the conductive path, are always seen some cracks perpendicular to the current flow direction which seem to play an important role for the memory switching phenomena. The variation of the phase in the path, however, has not been detected by a direct method. To clarify the role of the path or its cracks, several kinds of samples were subjected to the measurements of their electrical properties accompanied by the successive cycles of heating and cooling. It was recognized that Fe₂O₄ samples quenched from the temperature over the region of the dissociation of α-Fe₂O₃ showed the same properties as switching samples'. The formation of conductive path, its construction, and their role have been discussed. In the conductive path some α-Fe₂O₃ can be partially reduced to Fe₂O₄ and the origin of the memory switching effects may be due to the reoxidized layer around the contact in the crack.