Crystal Structure Stabilization of Gadolinium Aluminum Garnet (Gd<sub>3</sub>Al<sub>5</sub>O<sub>12</sub>) and Photoluminescence Properties

Abstract

To suppress the thermal decomposition and to stabilize the crystal structure of Gd 3 Al 5 O 12 (GdAG) garnet, doping GdAG with smaller Ln 3+ (Ln=Tb, Dy, Ho, Er, Tm, Yb, Lu, and Y, respectively) to form (Gd,Ln)AG solid solutions was proposed in work. Carbonate precursors of (Gd,Ln)AG with an approximate composition of (NH 4 ) x (Gd,Ln) 3 Al 5 (OH) y (CO 3 ) z •nH 2 O were synthesized via coprecipitation from a mixed solution of ammonium aluminum sulfate and rare earth nitrate, using ammonium hydrogen carbonate as the precipitant. The precursors and the calcination derived oxides were characterized using FT-IR spectroscopy, DTA/TG, XRD, BET and FE-SEM. The results showed that smaller Ln 3+ doping can indeed stabilize GdAG against its thermal decomposition to a mixture of GdAlO 3 (GdAP) and Al 2 O 3 phases at elevated temperatures and at the same time effectively lowers the temperature for garnet crystallization. The carbonate precursors are loosely agglomerated and the resultant (Gd,Ln)AG powders show good dispersion and a fairly uniform particle morphology. The (Gd,Ln)AG solid solutions exhibit decreasing lattice parameters along with decreasing radius of the dopant ions at the same dopant content of 50 at%. Photoluminescence properties of some of the garnet solid solutions are also studied. The materials developed herein may potentially be used for photoluminescent and scintillation applications.