Development of White Persistent Phosphors by Manipulating Lanthanide Ions in Gadolinium Gallium Garnets. Issue 3 (28th January 2021) - Ueda, Jumpei
Abstract : Lanthanide ions act as excellent luminescence centers and good charge carrier traps. By selecting proper lanthanide ions, persistent phosphors with the desired luminescent color can be developed. In addition, an appropriate host material can give not only better persistent luminescence performance but also an additional function. Herein, bright white persistent phosphors of Pr 3+ –Tb 3+ –Eu 3+ tridoped paramagnetic Gd3 Ga5 O12 (GGG) are successfully developed. The GGG phosphors singly doped with Pr 3+, Tb 3+, and Eu 3+ show reddish‐white ( 3 PJ – 3 HJ ), blue ( 5 DJ – 7 FJ ), and red ( 5 D0 – 7 FJ ) photoluminescence, respectively, by UV excitation. On the other hand, the GGG samples codoped with Pr 3+ –Eu 3+ and with Tb 3+ –Eu 3+ show only Pr 3+ reddish‐white persistent luminescence and Tb 3+ blue persistent luminescence, respectively. Based on the thermoluminescence glow curves, it is found that the Eu 3+ ion acts only as an electron trap in the persistent luminescence mechanism and the trapped electrons are released at around 325 K. The cool‐white persistent luminescence is achieved by combining Pr 3+ and Tb 3+ persistent luminescence centers in the GGG:Pr 3+ –Tb 3+ –Eu 3+ phosphors. It is demonstrated that the white persistent phosphor powder in water can be dragged around by a permanent magnet due to the paramagnetic property of GGG. Abstract : Persistent phosphors are developed in Gd3 Ga5 O12 (GGG) compounds by manipulating lanthanide ions with the help of the vacuum referred binding energy diagram. The persistent color is controlled by the combination of Tb 3+ and Pr 3+ and pure white persistent luminescence is realized. The paramagnetic GGG persistent phosphor is dragged by a magnet.