Multi-colour emission from ZnO[SO4]:Eu2+ nanophosphors: Effects of SO42- and Eu2+ doping concentration

Blue-emitting ZnO-SO4:Eu2+ powder phosphors were synthesized via solid state reaction method. Based on the X-ray diffraction (XRD) data, hexagonal wurtzite structures of ZnO were formed. Further structural elucidation via Raman spectroscopy showed a peak at 439 cm−1 associated with E2hgh optical mode that is a distinctive characteristic band of hexagonal wurtzite ZnO phase. The ZnO powders were composed of distorted spherical nanoparticles, which were agglomerated together as confirmed from scanning electron microscopy images. After incorporation of SO42- and Eu2+ into the ZnO lattices sites, the particle shapes became irregular. When excited at 351 nm with Xenon lamp, our samples emitted UV and blue-green visible light associated, respectively, with excitonic recombination and intrinsic structural lattice defects in ZnO. Both the photoluminescence (PL) peak intensity and positions of these emissions were influenced by SO42- and Eu2+ ions. The blue emission was dependent on the Eu2+ content with the largest intensity measured from the sample doped with 1.0 mol% of Eu2+ ions. Mechanisms of energy transfer and concentration quenching effect are discussed. [Display omitted] •A series of Eu2+ doped ZnO-SO4 nanophosphor was synthetized through the solid-state reaction technique.•The effects of the SO42- anionic group on the photoluminescent properties of ZnO:Eu2+ nanophosphors were examined.•Photoluminescence behaviour of ZnO-SO4:Eu2+ nanophosphors were analysed using near‐band edge and deep-level emissions.•Simplified energy transfer mechanisms of light emission was identified.•Optimized Eu2+ blue colour emission can be commercially applied in White-LED devices.