Upconversion luminescence properties of Y2O3 nanocrystals doped with trivalent rare-earth ions

Upconversion luminescence properties of Y2O3 nanocrystals doped with Er3+ and codoped with Er3+ and Yb3+ under excitation with a 980 nm laser diode have been studied. The green and red luminescence, which are attributed to the H-2(11/2) to I-4(15/2), S-4(3/2) to I-4(15/2), and F-4(9/2) to I-4(15/2) transitions of Er3+, have been observed from Y2O3 nanocrystals doped with Er3+ as well as those codoped with Er3+ and Yb3+. Photoluminescence properties of three transitions of Er3+, related to the Er3+ concentration in Y2O3 nanocrystals and Yb3+ concentration in Y2O3 nanocrystals doped with 1 mol % Er3+, have been investigated in detail. For Y2O3 nanocrystals doped with 1 mol % Er3+, the slope values of the line corresponding to the photoluminescence intensities of the three transitions as a function of pump power are approximately 2 due to two-photon absorption by Er3+ only. Otherwise, for Y2O3 nanocrystals doped with 10 mol % Er3+ and codoped with 1 mol % Er3+ and 5 mol % Yb3+, both the slope values are less than 2. These results are related to the energy-transfer process of trivalent rare-earth ions. (c) 2005 The Electrochemical Society. [DOI: 10. 1149/1.1859691] All rights reserved.