Charge transport mechanism and the effect of poling on the current-voltage characteristics of conducting polyaniline–BaTiO3 composites

Conducting polyaniline–barium titinate (PANI–BaTiO3) composites have been synthesized by `in situʹ deposition technique by placing the fine grade powder of BaTiO3 (prepared by conventional sol–gel technique) in the polymerization reaction mixture of aniline — finally yielding the Polyaniline–BaTiO3 composites. The charge transport process in these composites have been studied by sandwiching the pellets of these composites between the silver and platinum electrodes. It presumably suggests presence of a nonlinear space charge controlled charge transport process. Also, a large hysteresis in the I–V characteristics of these composites has been observed which also supports the space charge controlled conduction. The samples were poled by applying a constant voltage for a fixed time and the I–V characteristics were traced before and after poling. Some striking differences have been observed in the I–V characteristics before and after poling. These have been explained on the basis of creation of an internal electric field due to poling which in turn opposes the externally applied electric field.