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Dai, W. B. (2014) Mechanism of the reduction and energy transfer between Eu2+ and Eu3+ in Eu-doped (CaAlSiO8)-Si-2-O-2 materials prepared in air. J. Mater. Chem. C, 2 3951–3959.
Added by: Florent Boucher (2016-04-29 09:26:45) |
| Type de référence: Article DOI: 10.1039/c3tc32378a Numéro d'identification (ISBN etc.): 2050-7526 Clé BibTeX: Dai2014b Voir tous les détails bibliographiques  |
Catégories: MIOPS Mots-clés: ba, ca, emission, fluorescence, light-emitting diodes, Luminescence, phosphor, sr, temperature, thin-films Créateurs: Dai Collection: J. Mater. Chem. C |
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| Résumé |
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Eu2+ doped CaAl2Si2O8 materials prepared under a reducing atmosphere show a white-bluish luminescence under UV excitation. Eu3+ cations naturally give rise to line emission spectra for which the colour of emissions is between orange and red. To achieve a warm color or to change the CIE(x, y) position of the Ca1-xEuxAl2Si2O8 phosphors, we decided to investigate the synthesis of these compounds under air conditions to favour the co-existence of Eu2+ and Eu3+ cations and investigate the mechanism of the "abnormal" reduction from Eu3+ to Eu2+ and the energy transfer from Eu2+ to Eu3+ in the "co-doped" CaAl2Si2O8 host lattice. The results indicate that both Eu2+ and Eu3+ co-exist in the aluminosilicates, even when synthesized under air conditions, due to the substitution of Eu3+ cations for alkaline earth metal (Ca2+) triggering the formation of vacancies that play the role of electron donors towards V"Ca defects. The higher the concentration of V"Ca, the easier the reduction of Eu3+ into Eu2+. Consequently, the "co-doping" with higher state chemical elements (e.g. Zr4+) may help a lot in increasing the concentration of Eu2+ cations at the expense of Eu3+. We will take advantage of this observation in the future for sure to help prepare materials.
Added by: Florent Boucher |