Low-temperature upconversion spectroscopy of nanosized Y2O3:Er,Yb phosphor -: art. no. 063529

This work reports on the structural characterization and on the low-temperature upconversion spectroscopy of the Y2O3:2%Er,1%Yb nanophosphor prepared by thermal decomposition of a polymeric resin (Pechini's method [U.S. Patent No. 3,330,697 (July 11 1967)]). The average particle size evaluated from transmission electron microscopy lies in the range of 05-25 nm. The high-resolution upconversion luminescence spectrum at 10 K in the ultraviolet to near infrared (UV-NIR) spectral regions shows narrow lines, characteristic of Er3+ transitions occupying both Y3+ sites with point symmetries C-2 and C-3i in the oxide cubic system. The excitation spectrum at 10 K in the IR region was used to monitor the green upconversion and IR luminescences and it displayed Er and Yb lines. Power dependence measurements at 298 and 10 K indicate that the main upconversion mechanism is a two-photon excitation process. The temperature dependence of the upconversion luminescence shows a decrease in the emission intensity with increasing temperature, and such decrease is much more evident for the emission in the violet than in the green and the red regions. (c) 2005 American Institute of Physics.