Improvement of multiferroic and leakage property in monophasic BiFeO3

This paper aims to report that impurity phase free single phase multiferroic BiFeO3 ceramic can be prepared by critically optimizing the metal ion concentration using slow step sintering schedule at 850 °C for 24 h. Antiferromagnetic character of pure BiFeO3 is completely changed and ferromagnetic behavior observed with increase of Bi as well as decrease of Fe concentration. It is found that Bi rich (Bi: 1.2) Fe deficient (Fe: 0.8) composition produces single phase rhombohedral structure with space group R3c along with enhanced ferroelectric and ferromagnetic properties. Incorporation of excess bismuth caused structural distortion and expected to compensate Bi loss during high temperature sintering. On the other hand, iron deficient helps the formation of Fe3+ state, which hinders the creation of oxygen vacancies and also favors the reduction of leakage current. Structural distortion in BiFeO3 changes Fe–O–Fe bond angle or spin order, destructs the spin cycloid and releases a locked magnetization.

► Excess Bi compensate Bi loss during high temperature sintering. ► Incorporation of excess Bi caused structural distortion. ► Iron deficient helps the formation of Fe+3 state and reduce leakage current. ► Slow step sintering schedule suppresses formation of impurity phase in Bi1.2Fe0.8O3.