Size dependence of the luminescence spectra and dynamics of EU3+: Y2O3 nanocrystals

We report the optical spectra and lifetimes of nanocrystalline Eu3+ : Y2O3 as a function Of particle diameter from 15 to 7 nm. As the particle size decreases, the spectra show increased line broadening and the emergence of a disordered phase. The 7-nm sample also contains cubic-phase material in addition to the monoclinic phase that is usually produced by the gas-phase-condensation synthesis. The D-5(0) lifetimes increase by more than a factor of two when the particle size decreases from approximately 15-7 nm, with the decay transients becoming non-single exponential For the 13-nm and smaller particles. (C) 1999 Elsevier Science B.V. All rights reserved.