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 de
creases, the spectra show increased line broadening and the emergence of a
disordered phase. The 7-nm sample also contains cubic-phase material in add
ition to the monoclinic phase that is usually produced by the gas-phase-con
densation 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.