Investigation on Luminescent Properties of Rare Earth Doped Mullite Phosphors and the Occupation Site of the Doped Rare Earths. Issue 9 (1st January 2019)

• Record Type: Journal Article
• Authors: Takahashi, Hirotaka; Matsushima, Yuta
• Is Part Of: Journal of the Electrochemical Society. Volume 166:Issue 9(2019)
• Page Start: B3209
• Page End: B3217
• Publication Date: 2019-01-01
• Subjects: Luminescence -- Solid-State Topics: General -- Mullite -- R-G-B phosphors -- Rare-earth; Electrochemistry -- Periodicals; 541.3705
• DOI: 10.1149/2.0321909jes
• Languages: English
• ISSNs: 0013-4651

Abstract

Abstract : Full color phosphors based on a host material of mullite (Al6 Si2 O13 ) doped with rare earth (Ce 3+, Eu 2+, Ce 3+ -Tb 3+, and Eu 3+ ) were investigated for the possible application for high power LED lightings. Doping these rare earth ions separately resulted in blue, green and red emissions. The mullite phosphors kept 70% of the luminescence intensity even at 200°C, which was explained by the low thermal lattice vibration associated with the low thermal expansion coefficient. Based on the ionic radii and the bond valence sums, the rare earth ions were considered to occupy the vacant Oc site surrounded by 8 oxygens with a void of 2.14 Å in diameter. Electron density mapping derived from the Rietveld analysis revealed the excess electron density around the Oc site as the possible occupation site for the rare earth ions.