Investigations on charge accumulation and relaxation in polycrystalline Al2O3: Correlations of surface potential measurements with other techniques

Polycrystalline alumina plates have been charged by different methods (contact/corona), at temperatures from 300 to 500 K, and fields from 0.2 to 15kV/mm. The accumulation and relaxation of this charge has been studied using surface potential decay and voltage return techniques, together with current, Thermal Step Method (TSM) and Thermo Stimulated Currents (TSC) measurements. The observed conduction regime appears as nearly ohmic, but evidence of inner space charge effects is observed. An interfacial polarization model is proposed.