Structural, optical, and enhanced multiferroic properties of xCoFe₂O₄-(1 − x)K_0.5Bi_0.5TiO₃ ferrite–ferroelectric composites

Multiferroic ferrite–ferroelectric composites with general formula xCoFe₂O₄-(1 − x)K_0.5Bi_0.5TiO₃ (x = 0.0, 0.3, 0.5, 0.7, and 1.0) (xCFO-KBT) were developed by conventional solid-state reaction method. The structural, optical, magnetic and ferroelectric properties for the prepared samples were studied in detail. Two individual structures of spinel-type ferrite and tetragonal-type ferroelectric are characterized through X-ray diffraction while Raman scattering spectra and SEM analyses furtherly confirm the coexistence of the two phases in the composites. The bandgaps calculated for the composites narrow dramatically compared with the pure KBT, which are attributed to Co²⁺d–d on-site transitions from the CFO phase. The magnetic property transforms from diamagnetism for pure KBT to ferromagnetism for the composites and pure CFO with saturation magnetization M_s increasing gradually with addition of CFO. Besides, the room temperature ferroelectricity has been detected in the composites, which turns out to be enhanced by space charge contribution of CFO phase. The improvement of optical and multiferroic properties in the composites indicates great prospect on visible-light optical devices and non-volatile data storage.