Enhancment of ferromagnetism in Ba and Er co-doped BiFeO₃ nanoparticles

Bi_1−y−xBa_yEr_xFeO₃ [BB_yE_xFO, (0.13≤y≤0.17, 0≤x≤0.2)] nanoparticles were successfully synthesized by a sol–gel method. The structural, microstructural and magnetic properties have been investigated, using X-ray diffraction, Raman scattering, field emission scanning electron microscopy (FE-SEM) and magnetometry measurements at room temperature. The refinement of X-ray diffraction pattern of BB_0.15E₀FO indicates a phase transition from rhombohedral (R3c) to tetragonal (P4mm) with increasing Ba content and a transition from the coexistence of rhombohedral–tetragonal phase to orthorhombic (Pbnm) in BB_0.15E_xFO samples with increasing Er concentration. The Raman analysis confirms crystal phase transition in BB_0.15E_xFO compounds. The FE-SEM and TEM analysis show that the average nanoparticle size is about 50–100 nm and it decreases with Er concentration. The remnant magnetisation of BB_0.15E_0.1FO sample (M_r=0.98 emu/g) is approximately two times greater than compared to BB_0.15E₀FO (M_r=0.51 emu/g) that may be attributed to the collapse of spin structure and modifying exchange interactions because of Er⁺³ doping. This enhancement in magnetic properties at room temperature can play an important role for the practical applications. - Highlights: • Bi_1−y−xBa_yEr_xFeO₃ nanoparticles were successfully synthesized by a sol–gel route. • X-ray diffraction and Raman spectroscopy measurements confirmed a phase transition from rhombohedral–orthorhombic. • Considerable enhancement in magnetisation of BiFeO₃ is obtained with Ba and Er co-doping