Synthesis, crystal structure, and optical properties of MgO-doped jeanbandyite for optoelectronic applications

MgO-doped FeSnO(OH)₅ was synthesized via a solid-solid mixing route followed by ultrasonication. X-ray diffraction with Rietveld refinement confirms retention of the cubic crystal structure upon doping. Atomic force microscopy reveals a compact polycrystalline surface with well-defined nanoscale features. X-ray photoelectron spectroscopy (XPS) confirms the presence of Fe, Sn, Mg, and O in their expected oxidation states, supporting successful incorporation of MgO into the host lattice. UV-Vis spectroscopy shows strong absorption in the violet-blue region, consistent with a direct optical transition. Optical constants-including refractive index, extinction coefficient, dielectric function, electric modulus, and optical conductivity-exhibit pronounced dispersion, reduced high-energy dielectric losses, and enhanced near-band-edge conductivity. Urbach energy analysis indicates disorder-related effects, while the Wemple-DiDomenico model describes the dispersion behaviour. Nonlinear optical analysis reveals enhanced third-order susceptibility and nonlinear refractive response. Polarization-electric field measurements indicate predominantly non-ferroelectric, lossy dielectric behaviour with weak nonlinear polarization. Overall, these findings highlight the potential of MgO-doped jeanbandyite for optoelectronic and photonic applications.