Precise Control of Structure and Magnetic Properties of BiFeO3: From Synthesis to Prediction of New Modifications

In recent years multiferroics have been an intriguing study field due to their well- known magnetoelectric phenomena that offer a wide range of potentially new applications including spintronics, new data storage media and multiple-state memories [1–5]. Bismuth ferrite (BFO) particles were synthesized via a controlled hydrothermal method, yielding highly pure, small-sized particles. Structural characterization revealed that the as-synthesized (non- annealed) powder crystallizes in the rhombohedral R3c space group with minimal secondary phase content. Upon annealing at 800 °C, a single-phase perovskite structure with high crystallinity was obtained. High-resolution transmission electron microscopy (HRTEM) analysis confirmed the presence of twin stacking faults, which are responsible for enhanced magnetic properties. Electron paramagnetic resonance (EPR) spectroscopy measurements suggested the existence of electrons trapped by vacancies or defects. It has been proposed that the existence of Fe3+−OV defect complex could be generated at elevated temperatures followed by the formation of trivalent Fe ions, which intensely provide local 3d moments. In addition, a structure prediction has been performed and 11 additional BiFeO3 modifications have been proposed, while the magnetic behavior of synthesized material was investigated by SQUID.