Dual co-doping strategy for prolonged luminescence in laser-sintered BaAl₂O₄:Eu²⁺, RE³⁺ ceramics

This work reports on the influence of co-doping on the luminescence and persistent luminescence properties of BaAl₂O₄ (BaO·Al₂O₃) laser-sintered ceramics. The samples were doped with Eu and doubly co-doped with different rare earths (Dy, Er, Nd, Pr, and Tm) followed by laser-sintering without an atmospheric control, at a power density of 1.6 W/mm². All sintered ceramics contained the hexagonal BaAl₂O₄ phase and had a homogeneous microstructure. A photoluminescence emission band centered at 495 nm was observed, which was due to the 4f⁶5 d¹ → 4f⁷ Eu²⁺ transition in the BaAl₂O₄ matrix. The persistent luminescence emission was monitored for 15 min after charging at 345 nm for 3 min. The combination of Nd and Dy co-doping led to substantial improvements in decay time and persistent luminescence intensity compared to individual co-doping. These results suggested that the two co-dopants interacted by modifying the trap configurations in the BaAl₂O₄ matrix.