Pressure-Induced Abnormal Electrical Transport Transition from Pure Electronic to Mixed Ionic-Electronic in Multiferroic BiFeO3 Ceramics

Pressure-induced structural changes could induce changes in transport properties and lead to a better understanding of the structure-property relationship. The evolution of the carrier transport properties of BiFeO3 (BFO) ceramics under a high pressure was investigated through impedance spectroscopy measurements at room temperature combined with first-principles calculations. A pressure-induced abnormal transition from pure electronic to mixed ionic-electronic was found in the BFO ceramics Cmmm and Pnma phases at 7.67 and 11.01 GPa, respectively. The pressure-induced structural phase transition from the R3c phase to Cmmm and then to Pnma was responsible for the change in electrical transport behavior from pure electronic to mixed ionic- electronic conduction, accompanied by a decrease in ionic resistance. The calculations of electronic structures and electron localization function from 1 atm to 40 GPa indicated that the ionic conduction in the Pmma phase resulted from the weakened Coulomb screen of the localized electron background to O( )(2+)between Bi3+ and O2+. This work provides a critical insight into the understanding of the relationship between structure and conduction and facilitates the application of ferroelectric materials in photoelectric fields.