Modulating the electric and magnetic properties of BiFeO3 ceramics

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 (V-Fe) and oxygen (V-O) vacancies and Bi2O3 deficiency mainly leads to the formation of bismuth (V-Bi) and oxygen vacancies (V-O). 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 d(33). Surprisingly, Bi2O3 excess, widely used for fabricating BFO ceramics with better properties in the past, cannot improve d(33). An enhanced piezoelectricity (d(33) = 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 (2P(r) similar to 90-119 mu C/cm(2)) and a tunable magnetization (M-r = 0.022-0.038 emu/g and H-c = 0.87-4.04 kOe) 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.