Greatly enhanced Dy3+ emission via efficient energy transfer in gadolinium aluminate garnet (Gd3Al5O12) stabilized with Lu3+

Dy3+-doped and Lu3+-stabilized gadolinium aluminate garnet solid solutions of [(Gd1-xLux)(1-y)Dy-y](3)Al5O12 (x = 0.1-1.0, y = 0-0.10) have been developed as efficient phosphors for simultaneously strong blue (similar to 483 nm, the F-4(9/2) -> H-6(15/2) transition of Dy3+) and yellow (similar to 584 nm, the F-4(9/2) -> H-6(13/2) transition of Dy3+) emissions. The efficient energy transfer from Gd3+ to Dy3+ produces an additional excitation band, being the strongest, at similar to 275 nm that corresponds to the S-8(7/2) -> 6I(J) intra-f-f transition of Gd3+. With the energy transfer, significantly stronger Dy3+ emission (roughly two-fold) was obtained through excitation of Gd3+ at 275 nm rather than direct excitation of Dy3+ at 352 nm (H-6(15/2) -> 4I(11/2) + 4M(15/2) + 6P(7/2)I transition, the strongest intra-f-f transition of Dy3+). The quenching concentration of Dy3+ was determined to be similar to 2.5 at%, and the quenching mechanism was suggested to be dipole-dipole interactions. At the optimal Dy3+ content of 2.5 at%, increasing Lu3+ substitution tends to weaken both the excitation and emission bands owing to the higher electronegativity of Lu3+. Comparative studies showed that the best luminescent [(Gd0.8Lu0.2)(0.975)Dy-0.025]AG phosphor has an integrated emission intensity roughly 2.5 and 4 times those of its (Y0.975Dy0.025)AG and (Lu0.975Dy0.025)AG counterparts, respectively. The effects of processing temperature and Lu3+/Dy3+ contents on phase evolution, crystal structure, particle morphology, PLE/PL properties, and fluorescence lifetime of the phosphor are thoroughly investigated. Owing to its enhanced emission and high theoretical density, the (Gd,Lu)AG:Dy3+ phosphor developed in this work may potentially be used as a new type of photoluminescent and scintillation material.