Engineering structural distortions through transition-metal substitution provides a powerful pathway to tune the electronic properties of complex oxides. In this work, we investigate the impact of Mn 3 + substitution on the structural, vibrational, electronic, and morphological properties of hexagonal GdIn 1- x Mn x O 3 samples ( x = 0.00, 0.003, 0.02, 0.06, 0.08, 0.10, and 0.15) synthesized by the conventional solid-state reaction method. Structural analysis confirms the formation of a hexagonal perovskite phase crystallizing in the P6₃cm space group. Raman spectroscopy further supports this assignment by revealing the characteristic vibrational modes of this symmetry. The absorbance spectra show an evolution attributed to local distortions of the B-site coordination environment. First-principles calculations reveal that Mn substitution introduces spin-polarized Mn 3d states within the band gap, lowering the gap energy and generating localized magnetic moments that preserve the antiferromagnetic order in GdInO 3 . Morphologically, all samples exhibit dense polycrystalline microstructures composed of compact grains, with grain size and porosity varying with Mn content. The grain size distribution follows a log-normal behavior, with mean values ranging from ∼0.4 μm to 1.1 μm, showing a composition-dependent evolution and a tendency toward grain refinement at higher Mn concentrations.
Fajardo et al. (2026) studied this question.