Photoluminescent properties of new up-conversion phosphors of Yb/Tm co-doped (Gd1-xLux)3Al5O12(x=0.1-0.5) garnet solid solutions

The metastable garnet lattice of gadolinium aluminate garnet (Gd3Al5O12, GdAG) has been effectively stabilized by doping with significantly smaller Lu3+, which then allows a facile incorporation of rare earth activators for opto-functionality explorations. Carbonate precursors of Yb/Tm codoped (Gd, Lu)(3)Al5O12, with an approximate composition of (NH4)xLn(3)Al(5)(OH) y(CO3) z center dot nH(2)O (Ln = Gd, Lu, Yb and Tm), were coprecipitated from the mixed solution of ammonium aluminum sulfate and rare earth nitrates, using ammonium hydrogen carbonate as the precipitant. The resultant [(Gd1-xLux)(0.948)Yb0.05Tm0.002](3)Al5O12 (x = 0.1-0.5) garnet solid-solution particles, with good dispersion and fairly uniform particle morphologies, exhibit a strong blue emission centered at similar to 487 nm (the (1)G(4) -> H-3(6) transition of Tm3+) and a weak red emission centered at similar to 650 nm (the (1)G(4) -> F-3(4) transition of Tm3+) under laser excitation at 978 nm. Meanwhile, the dependence of up-conversion emission intensity on the pumping power was discussed. Partially replacing Gd3+ with Lu3+ up to 50 at.% (x = 0.5) does not appreciably alter peak positions of the up-conversion emission bands but tends to yield decreased lattice parameters of the material and lowered emission intensities. The Yb/Tm codoped (Gd, Lu) AG garnet system developed herein may potentially be used as a new type of optical material. (C) 2013 Elsevier B. V. All rights reserved.