Modulation of electric conduction in La-Mg codoped multiferroic BiFeO3 ceramics

The structural and conductive characteristics of La0.2Bi0.8Fe1−xMgxO3 (x = 0, 0.01, 0.02, 0.03, 0.04, 0.05) ceramics synthesized by a modified rapid sintering process are investigated and discussed. There is no any impure phase even in La0.2Bi0.8Fe0.95Mg0.05O3 ceramic, meanwhile, all samples show rhombohedral structure and the SEM micrograph shows that the ceramics are getting compact with the increase of Mg substitution. The AC impedance measurement reveals an obvious trend of transition from insulator to semiconductor upon doping Mg. When x = 0.01-0.04, a threshold switching effect can be observed and the threshold voltage shows strong dependence on the Mg dopant level. This work suggests an effective method to modulate the conductivity of BiFeO3-based multiferroic materials with purephase structure by codoping with La and Mg at Bi and Fe site respectively.