Luminescence properties and electronic structure of Ce³⁺-doped gadolinium aluminum garnet

Highlights: • The luminescence properties of Ce³⁺ ions in (Y, Gd)₃Al₅O₁₂ are analyzed. • The Gd³⁺ → Y³⁺ substitution leads to increasing of Ce³⁺ noncubic crystal field splitting parameter. • The excitation spectra for the Ce³⁺ emission in GdAG contain bands at 6.67, 7.75, and 9.76 eV. • These features are due to the Ce³⁺-bound exciton formation and O 2p → Al 3s, 3p transitions. • Contributions from Al atoms to the conduction-band density of states are quite essential. - Abstract: Yttrium-gadolinium aluminum garnets (YGdAG) doped with Ce³⁺ ions have been prepared by co-precipitation method. The luminescent properties of Ce³⁺ ions in Gd_3(1−x)Ce_3xAl₅O₁₂ (x = 0.01) have been studied upon excitation in the 2–20 eV region. The substitution of Gd³⁺ for Y³⁺ in the garnet structure results in broadening the emission band and shifting its maximum towards the longer wavelengths. It was found that in addition to the 4f → 5d excitation bands of Ce³⁺ ions, the excitation spectra for the Ce³⁺ emission contain bands at 6.67, 7.75, and 9.76 eV. These bands are attributed to the Ce³⁺-bound exciton formation and O 2p → Al 3s, 3p transitions, respectively. Although gadolinium states dominate near the bottom of the conduction band of Gd₃Al₅O₁₂, contributions from Al_tetr and Al_oct atoms to the conduction-band density of states are evaluated as quite essential