The development of Ce(3+)-activated (Gd,Lu)(3)Al(5)O(12) garnet solid solutions as efficient yellow-emitting phosphors

Ce(3+)-activated Gd(3)Al(5)O(12) garnet, effectively stabilized by Lu(3+) doping, has been developed for new yellow-emitting phosphors. The powder processing of [(Gd(1−x)Lu(x))(1−y)Ce(y)](3)Al(5)O(12) solid solutions was achieved through precursor synthesis via carbonate precipitation, followed by annealing. The resultant (Gd,Lu)AG:Ce(3+) phosphor particles exhibit typical yellow emission at ∼570 nm (5d–4f transition of Ce(3+)) upon blue-light excitation at ∼457 nm (the (2)F(5/2)–5d transition of Ce(3+)). The quenching concentration of Ce(3+) was determined to be ∼1.0 at% (y = 0.01) and the quenching mechanism was suggested to be driven by exchange interactions. The best luminescent [(Gd(0.9)Lu(0.1))(0.99)Ce(0.01)]AG phosphor is comparative to the well-known YAG:Ce(3+) in emission intensity but has a substantially red-shifted emission band that is desired for warm-white lighting. The effects of processing temperature (1000–1500 °C) on the spectroscopic properties of the phosphors, especially those of Lu(3+)/Ce(3+), were thoroughly investigated and discussed from the centroid position and crystal field splitting of the Ce(3+) 5d energy levels.