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

Abstract

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.