Analysis of the Local Structure around Eu and Mn Ions in Alkaline-Earth Silicate Phosphors for White Light Illumination
- Mitsubishi Chemical Group Science and Technology Research Center, Inc., 1000 Kamoshida-cho, Aoba-ku, Yokohama, 227-8502 (Japan)
- Japan Synchrotron Radiation Research Institute, 1-1-1, Kouto, Sayo-cho, Sayo-gun, Hyogo, 679-5198 (Japan)
- High Energy Accelerator Research Organization, 1-1 Oho, Tsukuba, Ibaraki, 305-0801 (Japan)
M2SiO4-based phosphors (M: alkaline-earth metal) that emit red to blue light are expected to offer high color rendering to white light-emitting diodes (LEDs) in combination with blue or near-UV excitation sources. It is very important for the complete control of the emission color to understand the crystal field around the active elements (rare-earth and transition metals). XAFS spectroscopy is applied to a (Ba,Ca)2SiO4:Eu,Mn phosphor at Eu L3- and Ba, Ca, Eu, Mn K-edges to elucidate the local environments of Eu and Mn. Eu L3- and Mn K-edge XANES spectra showed that Eu and Mn are both divalent, like Ba and Ca. K-edge EXAFS spectra indicated that the local structures of Eu and Mn are similar to those of Ba and Ca, respectively. However, the curve-fitting analysis showed that the first coordination shell of Eu has two Eu-O bonds that are both shorter than the Ba-O bond. FEFF calculations were also performed based on a BaCaSiO4 model constructed from the crystal structure of KNaSO4. They suggested that Eu substitutes both of Ba and Ca sites with some structural modification while Mn is clearly at the octahedral Ca site that is the smallest of the substitution sites.
- OSTI ID:
- 21054671
- Journal Information:
- AIP Conference Proceedings, Vol. 882, Issue 1; Conference: XAFS13: 13. international conference on X-ray absorption fine structure, Stanford, CA (United States), 9-14 Jul 2006; Other Information: DOI: 10.1063/1.2644579; (c) 2007 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); ISSN 0094-243X
- Country of Publication:
- United States
- Language:
- English
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