Luminescent characteristic of the CsBr phosphor activated with Eu2+ and Mn2+ ions

Spectra of excitation and emission were measured at RI and 15 K in crystals quenched (Q) of CsBr:Eu2+, CsBr:Mn2+ and CsBr:Eu2+,Mn2+. Emission bands at 444, 480, 520 and 570 nm with different relative intensities are generated in the samples after UV excitation. The blue band at 444 nm was ascribed with unknown clusters or aggregated centers (AC) of dipoles type Eu2+-V-c(-) and insulated dipole centers (IDC) like Eu2+-O2-. The bands at 480, 520 and 570 nm were assigned to Cs4EuBr6 nanocrystals; AC containing MnBr42- units in tetrahedral symmetry and another yet unidentified AC defect, respectively. In crystals of CsBr:Eu2+,Mn2+ the excitation and emission spectra taken at 15 K show no clear evidence of an energy transfer mechanism. Instead, the results suggest that the emission is produced by direct excitation of the ions of Eu2+ and Mn2+. Accordingly, single- or double-doped CsBr crystals may contain the same type of defects, either AC and/or IDC. (C) 2013 Elsevier B.V. All rights reserved.