Y2O2S : Eu31 nanocrystals—synthesis and luminescent properties

Luminescent Y2O2S : Eu31 nanoceramics having an average particle size of 20 nm has been prepared through a gel–polymer thermolysis process employing a urea–formaldehyde resin. In this nanocrystalline system, large blue shifts (in relation to the bulk system) of y5000 cm21 and y2000 cm21 in the photoluminescence excitation bands corresponding to the excitonic region and the Eu31–ligand charge transfer region respectively have been observed. These may be explained by considering possible size dependent changes in optical electronegativity and quantum confinement effects occurring in this large bandgap semiconductor system