Comment on "A comprehensive exploration of optical properties of GdAlO₃:Cr³⁺"

A recent study by Souissi et al., Opt. Mater., 162 (2025) 116841, assigns emission features between 680 nm and 720 nm and a broad excitation band at 324 nm to the Gd³⁺⁶P_J → ⁸S_7/2 transitions. In this comment, we offer an alternative interpretation of these spectral features. The origin of these transitions is clarified by recording the excitation and emission spectra, along with decay profiles, for the optically active centers present in our pristine and Cr³⁺-doped GdAlO₃ samples. Our investigation reveals that these spectral features originate from octahedral-site Mn⁴⁺ in GdAlO₃. This reassignment is corroborated by previously reported spectroscopic data on Mn⁴⁺ in GdAlO₃. The Mn⁴⁺ is likely introduced as trace impurities either from the Al₂O₃ precursor or introduced inadvertently during synthesis.