A comprehensive exploration of optical properties of GdAlO3: Cr3+

Abstract

This study focused on the optical properties of the Cr³⁺-doped GdAlO₃ perovskite, through comprehensive analysis of its photoluminescence spectra. The GdAlO₃: Cr³⁺ perovskite, synthesized by a traditional solid-state process, crystallizes in the orthorhombic Pbnm space group, with Cr³⁺ ions substituting Al³⁺ ions in octahedral sites. Photoluminescence excitation and emission spectra of the material were obtained and assigned. The zero-phonon lines ZPL of the observed emission and excitation transitions associated with the Cr³⁺ ions, in the visible range, were determined, and the experimental spectral data were modelled by the Fourier transformation of the autocorrelation function, enabling the calculation of diabatic potential energy profiles for the ground and lowest energy excited states. Crystal field parameters were derived, providing insight into the electronic structure of Cr³⁺ in the O_h symmetry site. The results highlighted the significant impact of coordination on the electronic structure of Cr³⁺ ions, with a notably high nephelauxetic effect parameter (h = 1.44), indicating a high degree of covalency in the metal-ligand bonds. Energy transfer from Gd³⁺ to Cr³⁺ in GdAlO₃: Cr³⁺ was found to be significant, contributing to the enhancement of the deep-red emission of the compound attributed to the ²E_g(²G) → ⁴A_2g(⁴F) d-d transition of Cr³⁺. Finally, the CIE 1931 chromaticity coordinates of the photoluminescence emission of GdAlO₃:Cr³⁺ were determined, positioning the emission at the boundary of the chromaticity diagram, indicative of its high color purity and potential suitability for red light-emitting display applications.