Structural and luminescent properties of a Cr ³⁺ /Sm ³⁺ doped GdAlO ₃ orthorhombic perovskite for solid-state lighting applications

Abstract

The Cr³⁺ and Sm³⁺ doped GdAlO₃ perovskite with formula Gd_0.995Sm_0.005Al_0.995Cr_0.005O₃, was synthesized <i>via</i> a solid-state reaction method, and its structure, morphology, and photoluminescence properties were thoroughly investigated. The compound crystallizes in the orthorhombic <i>Pbnm</i> space group, with Cr³⁺ transition-metal ions substituting Al³⁺ in the octahedral symmetry site, and Sm³⁺ lanthanide (rare-earth) ions occupying the tetrahedral site. The material's morphology and chemical composition homogeneity were evaluated through Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray analysis. Photoluminescence excitation (PLE) and emission spectra (PL) were used to shed light on the electronic structure of the Cr³⁺ cations, through crystal field analysis in the <i>O</i> _h symmetry site. Theoretical studies enabled the precise assignment of the Cr³⁺ 3d-3d transitions. The intra-configurational 4f-4f transitions of Sm³⁺ resulted in a variety of excitation bands appearing in the high-wavelength range of the PLE spectrum. The photoluminescence studies supported the occurrence of energy transfer in the doped GdAlO₃ perovskite between Gd³⁺, Sm³⁺ and Cr³⁺ ions. The obtained results suggest the high potential of the synthesized material for solid state lighting applications.