Optical properties and switching behavior in Gd2O3:Er3+ nanophosphor

The upconversion (UC) efficient Gd2O3:Er3+ nanophosphor powder has been synthesized through the combustion route using urea as a reducing agent. The UC studies have been carried out using 532 nm excitation, and the samples show intense emission bands in ultraviolet (340 and 383 nm), blue (411, 458, 472. and 491 nm), and green (523 nm) regions of spectrum. Downconversion emission bands are also observed in green (550 nm) and red (672 nm) regions. The pump power dependence of the emission intensity shows that two photons are involved in creating one upconverted photon and that excited state absorption is the excitation mechanism. The excitation intensity stimulated switchinglike behavior has been observed in the intensities of some emission bands. Phonon assisted energy migration from the H-2(11/2) (S-4(3/2)) level to the upper F-4(5/2) and (4) F-7/2 levels, opening up a new channel for emission at a certain level of input power, is thought to be the probable cause of a switchinglike mechanism. The plasmalike continuum emission has also been observed at elevated excitation powers. (C) 2009 American Institute of Physics. [doi: 10.1063/1.3259370]