A narrow-band red-emitting K2LiGaF6: Mn4+ phosphor with octahedral morphology: Luminescent properties, growth mechanisms, and applications

A narrow-band K2LiGaF6: Mn4+ red phosphor with octahedra and self-assembled microspheres morphologies was prepared through the two-step co-precipitation and hydrothermal methods, respectively. The forming mechanism of the regular octahedral crystals and self-assembled microspheres have been explored by SEM and HRTEM. The Mn4+ doping concentration and reaction time were optimized for improving its optical properties. The emission intensity of K2LiGaF6: Mn4+ can still keep 87% when it worked at 150 degrees C, indicating its excellent thermal stability. Moreover, the as-prepared K2LiGaF6: Mn4+ have better photoluminescence intensity and thermal stability than the previously reported K2LiGaF6: Mn4+, which should be attributed the optimization of morphology and structure. Especially, the slight shift of peak position of K2LiGaF6: Mn4+ than K2LiGaF6: Mn4+ was also analyzed in detail. Finally, the as-prepared K2LiGaF6: Mn4+ phosphor was packaged on WLED through combining the YAG: Ce phosphor. Excellent warm white light with the CCT = 4296 K, R-a = 91, and luminous efficiency = 137.56 lm.W-1 was obtained, making it becoming the promising red phosphor candidates for white light-emitting diodes. (C) 2017 Elsevier B.V. All rights reserved.