Green synthesis and luminescent properties of seven coordination K 3 ZrF 7 :Mn 4+ red phosphor for warm WLEDs

The seven-coordinated K 3 ZrF 7 :Mn 4+ red phosphor was synthesized by green route. The structure, composition and morphology were characterized by X-ray diffraction, energy-dispersive X-ray spectrometer and scanning electron microscope, respectively. The prepared K 3 ZrF 7 :Mn 4+ phosphor can produce bright red light under 468 nm excitation. In addition, the influences of acids and surfactants on the luminescence performance of K 3 ZrF 7 :Mn 4+ were investigated. The concentration quenching phenomenon and thermal quenching mechanism of Mn 4+ in K 3 ZrF 7 host were discussed. Moreover, a warm WLED with low color temperature (CCT = 2782 K) and high color rendering index (Ra = 93.3) was achieved by combining a mixture of K 3 ZrF 7 :Mn 4+ and YAG:Ce 3+ with InGaN chip. All the results show that the K 3 ZrF 7 :Mn 4+ is a prospective red phosphor applied to WLEDs.