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

Abstract

Abstract 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)3Al5O12, with an approximate composition of (NH4)xLn3Al5(OH)y(CO3)z·nH2O (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)0.948Yb0.05Tm0.002]3Al5O12 (x = 0.1–0.5) garnet solid-solution particles, with good dispersion and fairly uniform particle morphologies, exhibit a strong blue emission centered at ∼487 nm (the 1G4→3H6 transition of Tm3+) and a weak red emission centered at ∼650 nm (the 1G4→3F4 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.