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Cooperative Energy Transfer and Frequency Upconversion in Yb3+–Tb3+ and Nd3+–Yb3+–Tb3+ Codoped GdAl3(BO3)4 Phosphors

Key Lab of Specially Functional Materials, Ministry of Education and Institute of Optical Communication, South China University of Technology, Guangzhou 510641, People's Republic of China.
Journal of Fluorescence (Impact Factor: 1.67). 08/2007; 17(5). DOI: 10.1007/s10895-007-0200-6

ABSTRACT Polycrystalline GdAl3(BO3)4 phosphors codoped with Yb3+/Tb3+ and/or Nd3+/Yb3+/Tb3+ have been synthesized by combustion method. Upon excitation with a 980 nm laser diode, an intense green upconversion luminescence has been observed in GdAl3(BO3)4:Yb,Tb phosphor. The quadratic dependence of the luminescence on the pump-laser power indicating a cooperative energy transfer process. Meanwhile, it is noticed that upon excitation with 808 nm laser diode, intense luminescence has clearly been detected in GdAl3(BO3)4:Nd,Yb,Tb phosphor. The luminescence intensity exhibits also a quadratic dependence on incident pump-laser power. However, no green-emission has been observed in GdAl3(BO3)4 phosphors codoped with Yb3+/Tb3+ or Nd3+/Tb3+ respectively upon excited at 808 nm laser diode. A proposed upconversion mechanism involving energy transfer from Nd3+ to Yb3+, and then a cooperative energy transfer process from two excited Yb3+ to Tb3+ has been presented.

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