Synthesis, Structure, and Performance of Efficient Red Phosphor LiNaGe4O9:Mn4+ and Its Application in Warm WLEDs. Issue 6 (11th March 2016)

• Record Type: Journal Article
• Authors: Li, Pengfei; Tan, Linling; Wang, Liping; Zheng, Jiayu; Peng, Mingying; Wang, Yuefei
• Editors: Guo, H.
• Is Part Of: Journal of the American Ceramic Society. Volume 99:Issue 6(2016)
• Page Start: 2029
• Page End: 2034
• Publication Date: 2016-03-11
• Subjects: Ceramics -- Periodicals; 620.1405
• DOI: 10.1111/jace.14168
• Languages: English
• ISSNs: 0002-7820

Abstract

Abstract : For phosphor‐converted warm white light‐emitting diodes (WLEDs), it is essential to find highly efficient red oxide phosphors, which are better chemically stable and benign to environment and can be prepared in a much milder condition. Here, we report a red phosphor LiNaGe4 O9 :Mn 4+ with a quantum yield up to 78% after systematic optimization in synthesis temperature, dopant concentration of Mn 4+, and sintering time. Best performance of the phosphor can be reached when it is synthesized in a mild reaction condition, that is, at 850°C for 3 h in air. The integrated emission intensity is more than four times stronger than commercial red phosphor 3.5MgO·0.5MgF2 ·GeO2 :Mn 4+ (MFG:Mn 4+ ) under a blue light excitation at 470 nm. Crystal structural analysis reveals that the high efficiency Mn 4+ exhibits in the compound is mainly due to the well separation of GeO6 groups from each other by GeO4 tetrahedra in the neighborhood and the ideal substitution of octahedral Ge 4+ site by Mn 4+ in view of both size and charge matches. The high performance of the phosphor encourages us to apply the blue absorbing red phosphor to WLED, which is based on combination of a blue LED chip and YAG:Ce 3+, and the warm perception WLED is therefore achieved with a color temperature of 3353 K.