Tailoring the structurally driven optical and electrical properties of Ba-Ti co-substitution on bismuth ferrite

Abstract

In this investigation, we systematically studied Ba and Ti co-substituted bismuth ferrite (BiFeO3) with the stoichiometric composition Bi1-xBaxFe1-xTixO3 [x = 0, 0.1, and 0.2]. The compounds were synthesized through solid-state reaction route, ensuring the formation of a homogeneous phase. Structural characterization was made using Rietveld-refined X-ray diffraction (XRD) analysis, which confirmed the stabilization of a rhombohedrally distorted perovskite structure with space group R3c. The refinement process also indicated slight lattice distortions with increasing Ba and Ti content, suggesting changes in the crystal symmetry due to substitution effects. Microstructural analysis using scanning electron microscopy (SEM) revealed an irregular grain size distribution across all samples, indicating variations in grain growth mechanisms influenced by Ba and Ti incorporation. Energy-dispersive X-ray spectroscopy (EDS) analysis validated the substitution of Ba and Ti into the BiFeO3 lattice structure without significant formation of secondary phases, as each element was detected. Studies which performed the UV-Vis spectroscopy to measure the optical bandgap confirmed a significant increase of the bandgap energy with increased concentrations of Ba and Ti. The bandgap widened from 2.37 eV for pristine BiFeO3 to 3.32 eV for the highest level of substitution (x = 0.2), assuring a strong influence of dopant-induced electronic structure modifications. Dielectric and impedance spectroscopy measurements were performed over a broad frequency range (10 Hz-4 MHz) at ambient temperature to analyze the material's electrical properties. The frequency dependence of these properties suggests that the incorporation of Ba and Ti influences the dielectric relaxation mechanism, rendering the material potentially suitable for high-frequency electronic applications. This increase suggests potential enhancements in the photocatalytic and optoelectronic device applications of the material.