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Title: Analysis of the Local Structure around Eu and Mn Ions in Alkaline-Earth Silicate Phosphors for White Light Illumination

Abstract

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.

Authors:
; ; ; ; ;  [1];  [2];  [3]
  1. Mitsubishi Chemical Group Science and Technology Research Center, Inc., 1000 Kamoshida-cho, Aoba-ku, Yokohama, 227-8502 (Japan)
  2. Japan Synchrotron Radiation Research Institute, 1-1-1, Kouto, Sayo-cho, Sayo-gun, Hyogo, 679-5198 (Japan)
  3. High Energy Accelerator Research Organization, 1-1 Oho, Tsukuba, Ibaraki, 305-0801 (Japan)
Publication Date:
OSTI Identifier:
21054671
Resource Type:
Journal Article
Resource Relation:
Journal Name: AIP Conference Proceedings; Journal Volume: 882; Journal 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)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; ABSORPTION SPECTRA; ABSORPTION SPECTROSCOPY; ALKALINE EARTH METALS; BARIUM SILICATES; CALCIUM SILICATES; COLOR; CRYSTAL FIELD; CRYSTAL STRUCTURE; EUROPIUM; EXCITATION; FINE STRUCTURE; LIGHT EMITTING DIODES; MANGANESE; MANGANESE IONS; MODIFICATIONS; PHOSPHORS; X-RAY SPECTRA; X-RAY SPECTROSCOPY

Citation Formats

Okamoto, Kaoru, Yoshino, Masahiko, Shigeiwa, Motoyuki, Mikami, Masayoshi, Akai, Toshio, Kijima, Naoto, Honma, Tetsuo, and Nomura, Masaharu. Analysis of the Local Structure around Eu and Mn Ions in Alkaline-Earth Silicate Phosphors for White Light Illumination. United States: N. p., 2007. Web. doi:10.1063/1.2644579.
Okamoto, Kaoru, Yoshino, Masahiko, Shigeiwa, Motoyuki, Mikami, Masayoshi, Akai, Toshio, Kijima, Naoto, Honma, Tetsuo, & Nomura, Masaharu. Analysis of the Local Structure around Eu and Mn Ions in Alkaline-Earth Silicate Phosphors for White Light Illumination. United States. doi:10.1063/1.2644579.
Okamoto, Kaoru, Yoshino, Masahiko, Shigeiwa, Motoyuki, Mikami, Masayoshi, Akai, Toshio, Kijima, Naoto, Honma, Tetsuo, and Nomura, Masaharu. Fri . "Analysis of the Local Structure around Eu and Mn Ions in Alkaline-Earth Silicate Phosphors for White Light Illumination". United States. doi:10.1063/1.2644579.
@article{osti_21054671,
title = {Analysis of the Local Structure around Eu and Mn Ions in Alkaline-Earth Silicate Phosphors for White Light Illumination},
author = {Okamoto, Kaoru and Yoshino, Masahiko and Shigeiwa, Motoyuki and Mikami, Masayoshi and Akai, Toshio and Kijima, Naoto and Honma, Tetsuo and Nomura, Masaharu},
abstractNote = {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.},
doi = {10.1063/1.2644579},
journal = {AIP Conference Proceedings},
number = 1,
volume = 882,
place = {United States},
year = {Fri Feb 02 00:00:00 EST 2007},
month = {Fri Feb 02 00:00:00 EST 2007}
}