Modulating the electric and magnetic properties of BiFeO3 ceramics

Abstract

In this work, the electric and magnetic properties of BiFeO3 (BFO) ceramics are modulated by changing the defect-dipoles using different Bi2O3 contents, where excessive Bi2O3 gives rise to the formation of iron (VFe) and oxygen (VO) vacancies and Bi2O3 deficiency mainly leads to the formation of bismuth (VBi) and oxygen vacancies (VO). It is of great interest to note that a rather low leakage current density can be achieved in both Bi2O3 deficient and excessive ceramics. We also find that a moderate level of Bi2O3 deficiency (<9%) has little influence on d33. Surprisingly, Bi2O3 excess, widely used for fabricating BFO ceramics with better properties in the past, cannot improve d33. An enhanced piezoelectricity (d33=49–51 pC/N) can be obtained in the BFO ceramics with a wide Bi2O3 content range (i.e., x=−0.09–0.09). A large remanent polarization (2Pr~90–119μC/cm2) and a tunable magnetization (Mr=0.022–0.038emu/g and Hc=0.87–4.04kOe) are achieved in BFO ceramics with x=−0.15–0.15. These defect-dipoles induced by Bi2O3 deficiency or excess can well modulate the electric and magnetic properties of BiFeO3 ceramics.