Enhancement in magnetic properties of Ba-doped BiFeO3 ceramics by mechanical activation

• Ba-doped BiFeO3 ceramics prepared by SSR reaction with and without ball milling.
• Nearly 50% increase in magnetization found in mechanically activated samples.
• Pre-alloying by mechanical activation leads to three folds increase in coercivity.
• Local magnetic behavior has been investigated by Mössbauer spectroscopic studies.

Here, we report on the enhancement in the magnetic properties of polycrystalline Bi1−xBaxFeO3 (x = 0.0, 0.05, 0.1 and 0.2) ceramic samples as a consequence of mechanical activated solid-state-reaction in comparison to standard solid-state-reaction processed samples. Our results suggest that mechanical activation has pronounced effect on the temperature of phase evolution as well as magnetic characteristics of Ba doped BiFeO3. The temperature, at which perovskite phase crystallizes is lower for mechanical activation assisted samples than for standard solid-state-reaction processed samples, attributed to pre-alloying during mechanical activation process. All the samples crystallize in a distorted perovskite structure with space group R3c and no structural change is found up to highest Ba doping. Mechanical activation also leads to significantly altered magnetic properties, particularly in higher Ba-doping samples which show about 50% increase in the magnetization and more than three fold increase in the coercive field. Local magnetic behavior investigated by 57Fe Mössbauer spectroscopy rules out any valence fluctuations of Fe and the hyperfine field corroborates the magnetization data.