Effects of HfO2 dopant on characteristics of Li2MgTiO4-based red phosphors: Thermal stability,photoluminescence intensity and quantum efficiency improvement |
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Authors: | Li-Fang Nien Chung-Hao Chiang Hsiau-Hsian Nien Sheng-Yuan Chu |
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Affiliation: | 1. Department of Electrical Engineering, National Cheng Kung University, Tainan 701, Taiwan;2. Department of Electrical Engineering, Chienkuo Technology University, Changhua 500, Taiwan |
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Abstract: | To produce natural and vivid color, the color rendering index of white light-emitting diodes (WLEDs) with single phosphors is usually lower than 70, which is problematic for LED applications. A commonly used method to resolve this issue is to enhance the red component of WLEDs. In the present study, Hf4+ and Mn4+ co-doped Li2MgTiO4 red phosphors are synthesized using a solid-state reaction method. When this red phosphor is excited at 397 and 468?nm, it exhibits weak reabsorption in the blue region and emits a broad and deep red emission band in the range of 640–750?nm, which is attributed to the 2Eg → 4A2?g transition. With 5?mol% HfO2 dopant, the photoluminescence intensity is enhanced by 1.45-fold and thermal stability is increased by 7.7%. Moreover, this red phosphor was applied to a red phosphor-in-glass (RPiG) optical device with a low-melting TeO2-B2O3-ZnO-Na2O-WO3 glass system. In the RPiG melting process, Li2MgTiO4:Mn4+, Hf4+ red phosphor triggered neither a chemical reaction nor severe degradation, indicating good thermal stability. Li2MgTiO4:Mn4+, Hf4+ has potential as a red emission material for warm WLED applications. |
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Keywords: | WLEDs RPiG |
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