Doping effect of Tb³⁺ ions on luminescence properties of Y₃Al₅O₁₂:Cr³⁺ phosphor

Tb³⁺or/and Cr³⁺ doped or co-doped Y₃Al₅O₁₂(YAG) garnets were prepared by a citric acid sol–gel method. Single-phase YAG, YAG:Tb³⁺,YAG:Cr³⁺and YAG:Cr³⁺,Tb³⁺powders were obtained already at 1000 °Cand were further annealed at 1600 °C to increase the crystallinity. All materials were characterized by X-ray diffraction (XRD), thermogravimetric (TG), photoluminescence (PL), reflection and photoluminescence decay measurements. Scanning electron microscopy (SEM) was used for morphology description. Luminescence measurements indicated that Tb³⁺ ions located at dodecahedral sites transfer absorbed energy to Cr³⁺ ions located at octahedral sites resulting quenched Tb³⁺ and strengthened Cr³⁺ emission in YAG:Cr³⁺, Tb³⁺ upon 273 nm excitation.