Band gap engineering and magnetic switching in a novel perovskite (1−x)KNbO_3−xBaNb_1/2Fe_1/2O₃

The phase transition, microstructure, optical and magnetic properties of a novel material (1−x)KNbO_3−xBaNb_1/2Fe_1/2O₃ (xKBNFO) have been investigated. X-ray diffraction and Raman scattering spectra analyses suggest that all the samples are polycrystalline perovskite structure with an obvious phase transition. Optical absorption spectra indicate that BaNb_1/2Fe_1/2O₃ (BNFO) doping has an effect on the energy band structure. The KBNFO ceramics exhibit the band gap (E_g) in the range of 1.72–2.48 eV, much smaller than the 3.25 eV E_g of KNbO₃ material. Furthermore, the KBNFO materials present room-temperature ferromagnetism, and the magnetism can be controlled by the BNFO doping content. These results are helpful in the deeper understanding of phase transition, band gap tunability, and magnetism variations in perovskite and show the potential roles in perovskite solar cells and multiferroic applications.