A comprehensive study of the structural, linear, and nonlinear optical properties of Fe doped BaTiO3 for optoelectronic applications

In this study, BaTi 1-x Fe x O 3 (x = 0.00, 0.05, 0.10) nanoparticles were synthesized via a sol-gel route to systematically investigate their potential in photonic applications through optical property analysis. X-ray diffraction analysis confirmed the formation of tetragonal perovskite phase (space group P4mm) with successful Fe 3 + substitution at Ti 4+ sites and no detectable secondary phases. Scanning electron microscopy (SEM) revealed uniform granular morphology with consistent particle distribution across all doping concentrations. UV–visible spectroscopy demonstrated progressive optical band gap E g narrowing and increased Urbach energy E u with incremental Fe doping, indicating enhanced lattice disorder, defect state formation and modified electronic band structure. Comprehensive linear optical characterization revealed systematic enhancement of refractive index, extinction coefficient, dielectric constant, optical conductivity, and static refractive index with increasing Fe content. Nonlinear optical properties exhibited marked improvement, with significant increases in nonlinear refractive index (n 2 ) and third-order nonlinear susceptibility (χ (3) ). These correlated structural, electronic, and optical modifications establish Fe-doped BaTiO 3 nanoparticles as promising materials for next-generation integrated photonic devices including high-speed optical switching, modulation and frequency conversion applications.