title: Contrasting behaviour of the co-activators in the luminescence spectra of Y2O2S:Tb3+,Er3+ nanometre sized particles under UV and red light excitation.
abstract: Nanometre sized particles of terbium and erbium co-doped yttrium oxysulfide up-converting phosphors were prepared by a urea homogeneous-precipitation method. Results from X-ray powder diffraction (XRPD), scanning electron microscopy (SEM) and photoluminescence spectroscopy studies on the microstructure and luminescent properties of the materials are reported. Upconversion emission was observed from the Er(3+) cations when particles were excited with laser light of 632.8 nm wavelength. Under these conditions no interactions between the Er(3+) cations and the Tb(3+) cations were observed. In contrast there was evidence from the Stokes emission of the Er(3+) cations under 254 nm excitation for an interaction between the Er(3+) and Tb(3+) cations reducing intensity of the latter's blue and green emission bands by cross relaxation processes.
authors.affiliation: Wolfson Centre for Materials Processing, Brunel University, Uxbridge, Middlesex UB8 3PH, UK.
authors.forename: Xiao
authors.initials: X
authors.lastname: Yan
authors.forename: George R
authors.initials: GR
authors.lastname: Fern
authors.forename: Robert
authors.initials: R
authors.lastname: Withnall
authors.forename: Jack
authors.initials: J
authors.lastname: Silver
mesh_terms: D003116:Color; D004871:Erbium / Q000737:chemistry* / Q000528:radiation effects; D008163:Luminescent Measurements / Q000379:methods*; D008422:Materials Testing; D049329:Nanostructures / Q000737:chemistry* / Q000528:radiation effects / Q000648:ultrastructure*; D010316:Particle Size; D013440:Sulfides / Q000737:chemistry* / Q000528:radiation effects; D013725:Terbium / Q000737:chemistry* / Q000528:radiation effects; D014466:Ultraviolet Rays; D015019:Yttrium / Q000737:chemistry* / Q000528:radiation effects
chemical_list: D013440:Sulfides; D013725:Terbium; C038559:yttrium oxide sulfide; D015019:Yttrium; D004871:Erbium