Mechanism of luminance decrease in BaMgAl{sub 10}O{sub 17}:Eu{sup 2+} phosphor by oxidation
- Matsushita Electric Industrial Co., Ltd., Kyoto (Japan). Lighting Research Lab.
- Tottori Univ., Koyama (Japan). Dept. of Electrical and Electronic Engineering
The mechanism of luminance decrease in blue emitting BaMgAl{sub 10}O{sub 17}:Eu{sup 2+} phosphor after annealing has been studied. It was shown experimentally that annealing in air oxidizes BaMgAl{sub 10}O{sub 17}:Eu{sup 2+} and substantially changes the Eu{sup 2+} ion to an Eu{sup 3+} ion. This is also deactivates the Eu{sup 2+} luminescent center, thus decreasing Eu{sup 2+} emission. Furthermore, the compound EuMgAl{sub 11}O{sub 19}, in which the valence of the Eu ion is trivalent, was detected in BaMgAl{sub 10}O{sub 17}:Eu{sup 2+} annealed at temperatures higher than 800 C as a resulting product of oxidation. It was demonstrated that BaMgAl{sub 10}O{sub 17}:Eu{sup 2+} was converted by oxidation into a mixture of the two compounds BaMgAl{sub 10}O{sub 17} and EuMgAl{sub 11}O{sub 19}, and resulting in a further decrease in luminance. This suggests that obstructing the formation of Eu(III)MgAl{sub 11}O{sub 19} during the annealing is essential for alleviating the decrease in luminance. Preparing BaMgAl{sub 10}O{sub 17}:Eu{sup 2+} having both superior crystallinity and completely stoichiometric composition has been found to be effective in alleviating the luminance decrease.
- Sponsoring Organization:
- USDOE
- OSTI ID:
- 289401
- Journal Information:
- Journal of the Electrochemical Society, Journal Name: Journal of the Electrochemical Society Journal Issue: 11 Vol. 145; ISSN JESOAN; ISSN 0013-4651
- Country of Publication:
- United States
- Language:
- English
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