Influence of Pr³⁺ substitution on the structural, optical, magnetic, and dielectric properties of Sr₂FeTiO_6−δ double perovskites

Double perovskite compounds Sr_2-xPr_xFeTiO_6−δ (x = 0.2, 0.4, 0.6, 0.8) were synthesized using a high-temperature solid-state reaction method. X-ray diffraction (XRD) analysis confirmed that all samples exhibit a cubic structure with a space group of Pm-3m. Rietveld refinement using the pseudo-Voigt function confirmed the formation of a single-phase compound with good reliability factors. Scanning electron microscopy (SEM) showed that the particles were spherical with minimal clumping and were uniform in size and shape. Energy dispersive X-ray (EDAX) analysis confirmed the presence of Sr, Pr, Ti, Fe, and O elements. The oxidation states of the constituent elements were validated by X-ray photoelectron spectroscopy (XPS), confirming the stability of the crystal structure. Diffuse reflectance spectroscopy indicated semiconductor-like behavior, with the energy band gap decreasing from 3.24 eV to 2.71 eV as Pr content increased. Dielectric studies showed a frequency and temperature-dependent dielectric constant increases with increasing Pr substitution from x = 0.2 to 0.8. Magnetic measurements revealed a transition from antiferromagnetic to ferromagnetic characteristic as the Pr concentration increased. These findings suggest that the synthesized Sr_2-xPr_xFeTiO_6−δ compounds are promising candidates for use in advanced electronic technologies, magneto-optical storage, optoelectronic devices, and sensor applications.