Effect of Fe Doping on the Structural, Morphological, Optical, and Magnetic Properties of Ca ₂ InTaO ₆ Double Perovskite

In this study, undoped and Fe 3+ ‐doped Ca 2 InTaO 6 double perovskite samples are successfully synthesized by conventional high‐temperature solid‐state method. The influence of Fe doping on the structural, morphological, optical, and magnetic properties is systematically investigated. X‐ray diffraction patterns refined by the Rietveld method confirm a single‐phase orthorhombic structure (Pbnm space group) for all samples, with slight variations in lattice parameters and unit cell volume consistent with Fe 3+ substitution at the In 3+ site. Scanning electron microscopy reveals agglomerated, irregular particles, while energy‐dispersive X‐ray spectroscopy verifies the presence of Ca, In, Ta, Fe, and O in near‐stoichiometric proportions. UV–Vis analysis shows a progressive narrowing of the bandgap with increasing Fe content, attributed to the introduction of intermediate energy levels within the band structure. Photoluminescence spectra under 325 nm excitation exhibit a broad red emission at ≈671 nm due to Fe 3+ 4 T 1 ( 4 G) → 6 A 1 ( 6 S) transitions, with intensity enhancement up to 10 mol% followed by concentration quenching. Magnetic hysteresis ( M–H ) curves indicates a transition from paramagnetic to weakly ferromagnetic behavior with increasing Fe 3+ content, attributed to Fe–O–Fe superexchange interactions and spin canting. These findings demonstrate that Fe doping effectively tailors the multifunctional optical and magnetic properties of Ca 2 InTaO 6 for potential photonic and spintronic applications.