Tunable emission and thermal sensitivity via energy transfer from Bi 3+ to Eu 3+ in BaY 2 Al 2 Ga 2 GeO 12

BaY 2 Al 2 Ga 2 GeO 12 (BYAGGO):Eu 3+ and BaY 2 Al 2 Ga 2 GeO 12 :0.03Bi 3+ , y Eu 3+ phosphors have been prepared via a high-temperature solid phase method. BYAGGO:Eu 3+ has a stronger characteristic emission of Eu 3+ at 592 nm attributed to magneto-dipole transitions under 245 nm excitation, indicating that Eu 3+ is more inclined to occupy the central lattice of the octahedron with inverted symmetry. The lattice of Eu 3+ ions expands to the asymmetric dodecahedron center in Eu 3+ and Bi 3+ ions co-doped in BYAGGO. The emission of BYAGGO:Bi 3+ overlaps the excitation of BYAGGO:Eu 3+ , implying that energy transfer (ET) from Bi 3+ to Eu 3+ is possible. Furthermore, the fluorescence decay lifetime is the direct proof of energy transfer in BaY 2 Al 2 Ga 2 GeO 12 :0.03Bi 3+ , y Eu 3+ . The energy transfer efficiency reaches 72% at y = 0.25. Finally, BYAGGO:0.03Bi 3+ , 0.09Eu 3+ phosphor is employed for a WLED device with a color temperature of 3825 K and a color rendering index (Ra) of 88.75.