Cooperative upconversion luminescence in Tb3+:Yb3+ co-doped Y2SiO5 powders prepared by combustion synthesis

Frequency upconversion (UC) luminescence via cooperative energy transfer (CET) process between pairs of Yb3+ and Tb3+ ions was investigated in Tb3+ :Yb3+ :Y2SiO5 crystalline ceramic powders prepared by combustion synthesis. Surface morphology and structure of the powders were investigated by scanning electronic microscopy and X-ray powder diffraction. Photoluminescence experiments were performed in Tb3+-singly doped samples using ultraviolet light (lambda=255 nm) and in Tb3+ :Yb3+ co-doped samples using a near-infrared (NIR) diode laser (lambda=975 nm). Upon excitation with the NIR diode laser, UC luminescence with an intense emission band centered at similar to 549 nm, corresponding to the 4f intraband D-5(4)-F-7(5) transition of Tb3+, along with less intense emission bands at similar to 490, similar to 590 and similar to 620 nm, corresponding to other D-5(4)-> F-7(J) transitions, was detected. The CET rate was estimated by analyzing the dynamics of UC luminescence with rate equations model of the electronic populations. (C) 2013 Elsevier Inc. All rights reserved.