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Combustion synthesis of Ca-alpha-SiAlON:Eu2+ phosphors with different Ca concentrations and diluent ratios

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Title: Combustion synthesis of Ca-alpha-SiAlON:Eu2+ phosphors with different Ca concentrations and diluent ratios
Authors: Saito, Genki Browse this author →KAKEN DB
Kunisada, Yuji Browse this author →KAKEN DB
Sakaguchi, Norihito Browse this author →KAKEN DB
Nomura, Takahiro Browse this author →KAKEN DB
Akiyama, Tomohiro Browse this author →KAKEN DB
Keywords: Phosphor
Oxynitride
SiAlON
Combustion synthesis
Issue Date: 15-Oct-2017
Publisher: Elsevier
Journal Title: Ceramics international
Volume: 43
Issue: 15
Start Page: 12396
End Page: 12401
Publisher DOI: 10.1016/j.ceramint.2017.06.106
Abstract: Yellow Ca-alpha-SiAlON:Eu2+ phosphors for white light-emitting diodes (LEDs) were synthesized by a facile combustion synthesis method using CaO, Eu2O3, alpha-Si3N4, Si, and Al as raw materials. Ca concentrations and diluent ratios were optimized to improve their luminescence properties. The lattice constant and luminescence properties improved as x increased from 0.4 to 1.2 in Ca(x)Si(12-(m+n))Al(m+n)OnN(16-n):En(0.06). The optimum value was x = 1.2. Scanning transmission electron microscopy combined with energy dispersive X-ray analysis detected segregation of Ca and Eu at grain boundaries, which decreased luminescence behavior in the x = 1.4 sample. The influence of Si and Si3N4 diluents was investigated by varying the diluent ratio phi = (CaO + Eu2O3 + alpha-Si3N4)/(CaO + Eu2O3 + a-Si3N4 + Al + Si). Changes in temperature and flame propagation speed were measured during combustion synthesis using two thermocouples. When phi, was less than 0.5, the combustion temperature exceeded 1600 degrees C and the synthesized material contained an amount of the high-temperature beta-SiAlON phase. At phi > 0.7, the reaction temperature fell below 1200 degrees C, and unreacted raw materials remained. The optimum value of phi was 0.6. The internal quantum efficiency of the product synthesized at x = 1.2 and (I, = 0.6 was approximately 35% under 450-nm excitation. According to electron probe X-ray microanalysis, composition varied within individual synthesized particles, which may explain the decrease in emission behavior relative to a commercial product.
Rights: © 2017. This manuscript version is made available under the CC-BY-NC-ND 4.0 license http://creativecommons.org/licenses/by-nc-nd/4.0/
http://creativecommons.org/licenses/by-nc-nd/4.0/
Type: article (author version)
URI: http://hdl.handle.net/2115/75760
Appears in Collections:工学院・工学研究院 (Graduate School of Engineering / Faculty of Engineering) > 雑誌発表論文等 (Peer-reviewed Journal Articles, etc)

Submitter: 齊藤 元貴

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