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Site and local structure of activator Eu2+ in phosphor Ca10−x(PO4)6Cl2:xEu2
Ist Teil von
Journal of solid state chemistry, 2013-10, Vol.206, p.69-74
Ort / Verlag
Amsterdam: Elsevier Inc
Erscheinungsjahr
2013
Link zum Volltext
Quelle
Elsevier ScienceDirect Journals
Beschreibungen/Notizen
The site and local structure of activator Eu2+ in phosphor Ca10−x(PO4)6Cl2:xEu2+ is investigated by experiment measurements, first-principle calculations and XAFS simulations. From first-principle calculations, the “local” structure [bond length L(M–O)≤R(M2+)+R(O2−)] of host shows a significant deformation (expansion) when Ca2+ is substituted by Eu2+, and Eu2+ should prefer 6h site to 4f site in the host. The d→f emission of Eu2+ at 4f site should show a longer wavelength than that of Eu2+ at 6h site. The XAFS measurement and simulations suggest that the Eu2+ in our Ca9.9(PO4)6Cl2:0.1Eu2+ sample mainly locates at 6h site. In the emission spectrum, two emission profiles of Ca9.9(PO4)6Cl2:0.1Eu2+ sample are obtained and assigned. The major one (2.71eV≈456nm) should be the emission of Eu2+ at 6h site. The minor one (2.61eV≈465nm) should be that of Eu2+ at 4f site.
The d→f emission of Eu2+ in Ca9.9(PO4)6Cl2:0.1Eu2+ can be assigned as: emission profile at 2.71eV and 2.61eV are Eu2+ at 6h and 4f site, respectively. [Display omitted]
•Eu2+ in Ca10−x(PO4)6Cl2:xEu2+ causes deformation to “local” structure.•Eu2+ should prefer 6h site to 4f site in the host from energy aspect.•Emission at 2.71eV and 2.61eV should be Eu2+ at 6h and 4f site.