Electric field–induced electronic conduction in bulk oxide ceramics

Field-induced electronic conduction is widely recognised in (a) materials whose resistance is dominated by interfacial Schottky barriers and (b) thin films that exhibit high field-induced filamentary conduction. A third category of (low) field-sensitive conduction occurs in bulk oxide ceramics that show enhanced hole conduction if they are acceptor-doped, but reduced n-type conduction if they are donor-doped. Examples in these two categories are acceptor-doped titanate perovskites [1] and rutile that is slightly oxygen-deficient [2]. More recently, reversible, field-induced electronic conduction has been demonstrated in yttria-doped zirconia ceramics [3] and a reversible, insulator-metal transition in Ca-doped BiFeO3 ceramics [4]. A survey of these phenomena and their characteristics will be presented and possible mechanisms, involving redox activity of oxygen in the oxide ceramic structures, discussed. Possible implications in a range of fields, including dielectric breakdown, lithium battery cathodes, memristive switching and insulator-metal transitions will be highlighted for discussion