Transition metal modified bulk BiFeO3 with improved magnetization and linear magneto-electric coupling

At present BiFeO3 (BFO) is the most attractive and sole example, which possesses low magnetization value, high leakage current and low polarization in ceramic form. Single-phase room temperature multiferroics are rare in nature. This paper deals with the improved magnetic and observed linear magneto-electric coupling in Co and Sm co-doped BiFeO3 ceramics synthesized by sol–gel process at low temperature ∼600 °C. As synthesized Bi0.9Sm0.10Fe0.95Co0.05O3 (BSFCO) showed high impurities phases (20%) over wide range of calcination temperatures. Impurity phases reduced drastically from 20% to 5% after leaching with nitric acid. However the electrical and the magnetic properties were almost the same for both phases. Well-defined magnetic hysteresis with high magnetic moment was found at room temperature. Ferroelectric polarization studies demonstrated similar values and shape as reported in literature for the pure bulk BFO. Linear magneto-electric (ME) coupling and weak ME coefficient (α) ∼ 0.6 e−10 s m−1 were observed in the co-doped BFO. The origin of the strong ferromagnetic property in our samples may be due to the presence of rare earth and transition metal ions at the lattice sites of BFO or due to impurity phase, since we have not seen any change in magnetization with reduction of impurity phase the later effect is more unlikely.

► Present composition (Bi0.9Sm0.10Fe0.95Co0.05O3 (BSFCO) have shown very high magnetization compared to parent BFO.
► The magnetic hysteresis loops are well saturated with high saturation magnetization 2.89 emu/gm (unpoled and unleached) and 2.18 emu/gm (poled and unleached) respectively.
► Converse ME coupling were found 0.8e−10 s m−1 (H||E) and 0.6–0.8 × 10−10 s m−1 (H⊥E) which are better than the single phase multiferroic obeying linear ME coupling.