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Eu31 Luminescence, Ce41 r Eu31 Energy Transfer, and White-Red Light Generation in Sr2CeO4

Abstract

Photoluminescence studies on pure and Eu31-doped Sr2CeO4 compounds are presented. The pure compound displays a broad band in its emission spectrum when excited with 254 nm, which peaks at 467 nm and is due to the energy transfer between the molecular orbital of the ligand and charge transfer state of the Ce41 ion. The excitation spectrum shows a broad band which peaks at 300 nm. From the spectral properties, it is established that Sr2CeO4 has good potential for application as a blue phosphor in low pressure mercury vapor lamps and in TV tubes. The Eu31 spectral features, when doped at the Ce41 site either singly or along with La31, have been studied and compared with the results obtained by doping the Eu31 ion at the Sr21 site. At low Eu31 concentrations (#4 mol %), the observed excitation and emission spectra reveal excellent energy transfer between Ce41 and Eu31. This energy transfer generates white light with a color tuning from blue-white to red-white, the tuning being dependent on the Eu31 concentration. At high Eu31 concentrations (5-15 mol %), these compounds exhibit efficient red emission under 254, 355, and 466 nm excitations. The observed luminescence properties of these compounds are similar to those of the known Y2O3:Eu31 red phosphor. The emission intensity of Sr2CeO4:Eu (>0.05) under 466 nm excitation is twice that of Y2O3:Eu. The results establish that the compound Sr2CeO4 is an efficient “single host lattice” for the generation of white and red lights under UV irradiation

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