Affiliation: | 1. Faculty of Materials, Metallurgy and Chemistry, Jiangxi University of Science and Technology, Ganzhou, PR China
Key Laboratory of Rare Earth Luminescence Materials and Devices of Jiangxi Province, Ganzhou, PR China
National Engineering Research Center for Ionic Rare Earth, Ganzhou, PR China;2. Faculty of Materials, Metallurgy and Chemistry, Jiangxi University of Science and Technology, Ganzhou, PR China |
Abstract: | It has been one of the hot issues to prepare the red-emitting Mn4+-doped fluoride phosphors with highly efficient and waterproofness for warm white-light-emitting diodes (WLEDs) by the green and environmentally friendly method. Herein, we design a novel green molten salt route to synthesize K2SiF6:Mn4+ red powder using molten NH4HF2 salt instead of HF liquor as the reaction medium. The results show that KMnO4 and MnF2 could produce Mn4+ in NH4HF2 molten salt through a reduction reaction, and the resulting Mn4+-doped K2SiF6 exhibited a bright red emission peaked at 632 nm under blue light excitation. The luminescence intensity of the as-obtained product after immersing into water for 24 hours maintain nearly 100% of that before soaking and emission peak shape remains unchanged. The thermal stability of the sample was evaluated by temperature-dependent luminescence spectral intensity during heating and cooling. Furthermore, a warm white-light-emitting diodes (WLEDs) with an excellent color rendering index (Ra = 87.1), lower correlated color temperature (CCT = 3536K), and high luminous efficacy (116.99 lm·W?1) was fabricated based on blue chip and K2SiF6:Mn4+ and commercial yellow phosphor (Y3Al5O12:Ce3+). |