Co-precipitation synthesis, luminescent properties and application in warm WLEDs of Na3GaF6:Mn4+ red phosphor

The Na3GaF6:Mn4+ phosphor was prepared by co-precipitation method in our work. The structure, morphology and composition have been characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy-dispersive X-ray spectrometers (EDS), respectively. The Na3GaF6:Mn4+ produces sharp red emission when excited by blue light at 465 nm. The effect of reaction parameters on its morphology and luminescence properties was researched. In addition, the crystal-field strength and emission mechanism of Mn4+ in Na3GaF6 were analyzed. Moreover, the concentration quenching mechanism was also investigated. Finally, using Na3GaF6:Mn4+ as red material, a warm WLED with low color temperature (3670 K), high color rendering index (Ra = 82) and luminous efficiency of 123 lm/W was achieved. Above results suggest that Na3GaF6:Mn4+ has latent application value in warm WLEDs.