Fabrication, Structure, and Magnetic Properties of Pure-Phase BiFeO3 and MnFe2O4 Nanoparticles and their Nanocomposites

We fabricated pure-phase BiFeO3 (BFO) and MnFe2O4 (MFO) nanoparticles as well as their nanocomposites (BMFO), and then we studied their structures and magnetic properties. Pristine BFO nanoparticles of 93.3 nm average diameter were successfully synthesized using the sot-gel method by varying the solvent condition and the precursor amount. Pristine MFO nanoparticles with a mean diameter of 70.5 nm were synthesized using the co-precipitation method entailing the optimization of the preheating and aging steps. The fabricated MFO nanoparticles showed mostly nanospheres with few nanocubes. The nanocomposite samples of 50 % MFO and 50 % BFO were fabricated through grinding and pelletization, followed by sintering under an inert atmosphere. The crystal structures of the pristine materials in the nanocomposites were well preserved. The magnetization values (M-s) of the BFO, MFO, and BMFO were 4.9, 52, and 33 emu/g, respectively. This latter M-s value was significantly higher than that of BFO, owing to the coexistence of Fe2+ and Fe3+ in its BFO phase and the incorporation of magnetic MFO. Two synthesis methods and material properties including the structural, morphological, magnetic, and oxidation states of the BFO-MFO nanocomposites were studied in order to achieve a high M-s value of 33 emu/g, which is higher than the bulk values of previously reported BFO-MFO composite samples.