The development of Ce3+-activated (Gd,Lu)3Al 5O12 garnet solid solutions as efficient yellow-emitting phosphors

Abstract

Ce3+-activated Gd3Al5O12 garnet, effectively stabilized by Lu3+ doping, has been developed for new yellow-emitting phosphors. The powder processing of [(Gd 1-xLux)1-yCey]3Al 5O12 solid solutions was achieved through precursor synthesis via carbonate precipitation, followed by annealing. The resultant (Gd,Lu)AG:Ce3+ phosphor particles exhibit typical yellow emission at ∼570 nm (5d-4f transition of Ce3+) upon blue-light excitation at ∼457 nm (the 2F5/2-5d transition of Ce3+). The quenching concentration of Ce3+ 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 [(Gd0.9Lu0.1) 0.99Ce0.01]AG phosphor is comparative to the well-known YAG:Ce3+ 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 Lu3+/Ce3+, were thoroughly investigated and discussed from the centroid position and crystal field splitting of the Ce3+ 5d energy levels. © 2013 National Institute for Materials Science.