Variation of fluorescence lifetimes and Judd-Ofelt parameters between Eu3+ doped bulk and nanocrystalline cubic LU2O3

The luminescent properties of 1 mol % Eu3+ -doped cubic Lu2O3 nanocrystals prepared by a combustion synthesis route were investigated. The visible emission spectrum of the europium doped Lu2O3 nanocrystals indicate that the structural environment surrounding the dopant Eu3+ ion is distorted when compared to a bulk sample with a micrometer particle size. From the resulting emission spectra, the Omega(2) and Omega(4) Judd-Ofelt intensity parameters were calculated. The lifetimes of the D-5(0) excited state for both the C-2 and C-3i sites were found to be nearly double that found for a similarly doped sample with larger particle size (bulk sample). This behavior is attributed to a change in the refractive index of the nanocrystalline material that in turn modifies the oscillator strength of the 4f <----> 4f transitions.