Structural and optical studies of ZnAl2O4:x% Cu2+(0 < x ≤ 1.25) nanophosphors synthesized via citrate sol-gel route

Nanocrystalline ZnAl2O4:x% Cu2+(0 < x <= 1.25) phosphor powders were prepared via the citrate sol-gel technique. The pure-phase cubic structures in this systems were verified by the powder X-ray diffraction. Energy Dispersive x-ray Spectroscopy analysis confirmed the presence of the expected elements (Zn, Al, O and Cu). Scanning Electron Microscopy showed that the morphology of the phosphor was dependent on the concentration of Cu2+. High-Resolution Transmission Electron Microscopy confirmed that the Cu2+ concentration does not significantly influence the crystallites sizes of the phosphors. Ultraviolet-visible spectroscopy results showed that the Cu2+ concentration influenced the band gap of the host. Photoluminescence results showed that the emission intensity of the powder sample was dependent on the Cu2+ concentration. The emission from the host lattice was observed at 394 nm, while Cu2+ showed major emission at 405 and minor emission at 574 nm. The emission at 405 nm was due to the 3d(8)4s(1) -> 3d(9) transitions of Cu2+. The Commission on Illumination color coordinate evidently showed shifts from the bluewish to the greenish region with an increase in Cu2+ concentration. (C) 2016 Elsevier B.V. All rights reserved.