Influence of concentration of Sm³⁺ ions on the luminescent characteristics in Y₃Al₅O₁₂ host

In this study, a series of Y₃Al₅O₁₂: Sm³⁺ luminescent materials with different Sm doping were successfully synthesized by the sol-gel combustion method, and characterized by X-ray diffraction (XRD) and photoluminescence (PL) spectrum to investigate the relationships among structure, luminescent properties and Sm³⁺ concentration, and the mechanism of self concentration quenching of Sm³⁺. It is found that the Sm³⁺ concentration has no effect on the crystal structure with the strongest excitation peak of 405 nm, corresponding to the ⁶H_5/2 → ⁴F_7/2 transition of Sm³⁺. At 405 nm excitation, the Y₃Al₅O₁₂: Sm³⁺ gives a red luminescence centered at about 617 nm (⁴G_5/2 → ⁶H_7/2). The suitable doping-concentration of Sm³⁺ in Y₃Al₅O₁₂ is 3 mol%, and the quenching mechanism is the cross relaxation (⁴G_5/2 + ⁶H_5/2 → ⁶F_9/2 + ⁶F_9/2) caused by the interaction of electric quadrupoles between Sm³⁺ ions.