Structural, optical and magnetic tunability in KBiFe2O5 multiferroics

KBiFe 2 O 5 , a highly promising multiferroic for perovskite solar cells, has been fabricated using a one-step thermal treatment method. The resulting products were characterized by X-ray diffraction, scanning electron microscopy and ultraviolet-visible-near-infrared spectroscopy. The effect of temperature on the formation of KBiFe 2 O 5 polycrystallites was assessed, and we found that the reaction temperature is the key factor in determining the optical properties of the final products. Pure multiferroic KBiFe 2 O 5 forms at a temperature of 850 °C with a narrow band gap of 1.65 eV, which is due to the stronger covalent character of Fe-O in FeO 4 than that in FeO 6 accompanying the inverted t 2g /e g orbitals of tetrahedra. The magnetic transition from paramagnetism to ferromagnetism corresponds to the site of Fe 3+ , and the magnetic moment modification in the ferromagnetic phase in KBiFe 2 O 5 could be correlated with the temperature and distortion of the unit cell. These results are helpful in the deeper understanding of the relationship between the crystal structure and the physical properties in perovskite-like oxides and show the potential role such materials can play in perovskite solar cells and multiferroic applications. KBiFe 2 O 5 , a highly promising multiferroic for perovskite solar cells, has been fabricated using a one-step thermal treatment method.