Synthesis and improved photoluminescence of a novel red phosphor LiSrGaF6:Mn4+ for applications in warm WLEDs.

Red phosphors composed of Mn4+-activated complex fluorides have attracted considerable attention for applications in warm white light-emitting diodes (WLEDs). In the present study, we report a facile strategy to synthesize a novel red phosphor LiSrGaF6:Mn4+ (LSGF:Mn) at room temperature, and we also discuss its formation mechanism. Mn4+ ions occupy Ga3+ sites located at the centers of distorted [GaF6]3- octahedrons and emit intense red luminescence when excited by UV or blue light. The effects of synthesis conditions such as the type of strontium salts, the concentrations of K2MnF6 and NH3·H2O, and the reaction temperature have been investigated. The luminescence intensity of the phosphor LSGF:Mn has been improved by optimizing the synthetic parameters. The as-prepared phosphor LSGF:Mn exhibits broad and intense absorption in the blue region and bright luminescence in the red region, which indicate that it is promising for applications in warm WLEDs.