Energy Transition between Yb3+-Tm3+-Gd3+ in Gd3+, Yb3+ and Tm3+ Co-doped Fluoride Nanocrystals

YF3: 20% Gd3+, 20% Yb3+, 0.5% Tm3+ nanocrystal has been synthesized by a hydrothermal method. The upconversion (UC) emission and energy transfer progresses between Gd3+-Yb3+-Tm3+ under a 980-nm continuous wave semiconductor laser diode excitation have been explored. The experimental results show that the violet and ultraviolet (UV) enhancement with Tm3+ upconversion emission occurs in the nanocrystal, and in the same time the UC emissions of Gd3+ from D-6(9/2), I-6(J), P-6(5/2), and P-6(7/2) states to the ground state S-8(7/2) are obtained, too. The dynamic analysis implies that, under 980-nm excitation, the nanocrystal dimension plays a key role in the efficient energy transfer processes between Gd3+-Yb3+-Tm-3tt based on the energy matching conditions. (C) 2011 Published by Elsevier B. V.