Investigation of doping effect on electrical leakage behavior of BiFeO3 ceramics

Bi0.9A0.1FeO3 (A = Ca, Sr and Ba) ceramics are synthesized by using the conventional solid state reaction method. X-ray diffraction analysis shows that all the ceramics have a hexagonal distorted perovskite structure with the space group R3c. It is found that A-site substitution with the smallest ionic radius ions Ca2+ among (Ca2+, Sr2+and Ba2+) effectively suppressed the leakage current. The oxygen vacancies increase with the increase of the doping ionic radius of the divalent cations (Ca2+, Sr2+ and Ba2+) in Bi0.9A0.1FeO3 ceramics. The dependence of the electric field on the leakage current is systematically illustrated by using two bulk-limited conduction mechanisms (space-charge-limited conduction and Poole-Frenkel emission) and other two interface-limited conduction mechanisms (Schottky emission and Fowler-Nordheim tunneling). The dependence of temperature on electrical conductivity and the XPS measurements illustrate that the Fe2+ transport behavior could be mainly responsible for the electrical leakage behavior of BAFO (A = Ca, Sr and Ba) ceramics.