Optimized photoluminescence properties of a novel red phosphor LiSrAlF6:Mn4+ synthesized at room-temperature

A red phosphor with a broad excitation band in blue region and sharp emission peaks in red region is needed for compensating the red components of white light-emitting diodes (WLEDs) by converting blue light with a yellow phosphor Y₃Al₅O₁₂:Ce³⁺ (YAG:Ce). The red phosphor LiSrAlF₆:Mn⁴⁺ (LSAF:Mn) with morphology of flaky particles about 50 μm in diameter has been synthesized by an ion-exchange reaction route at room-temperature in air. The as-synthesized phosphors were characterized by x-ray powder diffraction (XRD), scanning electron microscope (SEM), and temperature-dependent photoluminescence (PL) spectra. The excitation spectrum of LSAF:Mn shows a broad-band excitation from 400 to 500 nm that is due to the spin-allowed transition of ⁴A_2g → ⁴T_2g of Mn⁴⁺, indicating a potential application for solid state lighting. The optimal PL intensity of the phosphor LSAF:Mn has been obtained by optimizing the synthetic parameters.