Mn4+ doped fluorotitanate phosphors: synthesis, optical properties and application in LED devices

In this work, we report an optimized cation exchange route for the production of a narrow-band A2TiF6:Mn4+ (A = K, Na and Cs) red emitting phosphor using a small amount of non-toxic HAc solution instead of volatile and corrosive HF liquid. The crystal structure, morphology and doping amount of the A2TiF6:Mn4+ products were characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS) and atomic absorption spectrophotometry (AAS) in detail. The influence of the molar ratio of the raw materials, HAc concentration and reaction time on the photoluminescence behavior has been systematically investigated. Moreover, the role of HAc in the formation process is discussed in detail. By revealing its application in white light-emitting diodes (WLEDs) with tunable chromaticity coordinates and correlated color temperature, we confirm that the substitution of HAc for HF will increase the large scale production feasibility of the A2TiF6:Mn4+ red phosphor for the WLED industry.