Ionic Injected Current Transients in Strontium Titanate Single-Crystals

Current transients J(E,t,T) at high fields (E > 1 MV/cm) have been measured in SrTiO/sub 3/ crystals. The results are complex, with more than one transient peak time t/sub p/. t/sub p/ varies from ca. 100 ms to 100 s as a function of temperature T and voltage V. One peak displays the dependence t/sub p/=const. x (1/V) expected for the Many-Mark-Helfish cusp and may be due to space-charge-limited ionic conduction. The second peak is nearly voltage-independent and may arise from the Cox-Tredgold mechanism in which irreversible electrolytic reactions occur at the anode that facilitate hole injection. Both processes depend strongly upon the sample history.