The enhancement of luminescence in Co-doped cubic Eu2O3 using Li+ and Al3+ ions

The co-doping of Li+ and Al3+ ions drastically enhances the luminescence of cubic Eu2O3. The integrated emission intensity of D-5(0)-> F-7(J) bands (J=1-4) at 580-710 nm increases by a factor of about 6.7 in the co-doped Eu2O3 compared to the un-doped Eu2O3. In order to confirm that the co-doped ions were actually incorporated into the host lattice, the structural characteristics were studied using Raman spectroscopy, XPS, XRD, photoluminescence lifetime, and an SEM. These analyses consistently indicate a certain structural evolution in their results with an increase in the co-doping concentration. Variations in the crystal structure, the crystal morphology, and the intensity variation of the Raman modes at 465 and 483 cm(-1) are presented as the evidences showing the incorporation of the co-doped ions into the host. The luminescence enhancement is discussed in terms of concentration quenching, reduction of defect sites, and the modification of the local symmetry of the Eu3+ ions, especially in the inversion symmetry sites. (C) 2011 Elsevier B.V. All rights reserved.