Structure identification and strongly enhanced luminescence of Sr9Y2 (WO6)4 : Mn4+ phosphors by co-doping Mg2+ ions for plant growth LEDs

In this paper, we reported a novel far-red emitting phosphor Sr9Y2(WO6)(4): Mn4+ and alkaline earth metal Mg2+ ion co-doped phosphor Sr9Y2(WO6)(4): Mn4+, Mg2+. Systematical studies on its crystal structure and luminescence properties are carried out. X-ray powder diffraction confirmed that the pure phase Sr9Y2(WO6)(4): Mn4+ and Sr9Y2(WO6)(4): Mn4+, Mg2+ phosphors show a single phase. Upon 350 nm excitation, the phosphors could emit farred emission in the range of 600-800 nm, peaking at 680 nm (14,706 cm(-1)) due to the E-2(g)->(4)A(2g) transition, with broad spectra overlap with the absorption band of phytochrome P-FR. The optimal doping concentration, concentration quenching mechanism, as well as the content and temperature dependent decay times of Sr9Y2(WO6)(4): Mn4+ phosphors are studied in detail. Impressively, Mg2+ dopant is found to strongly improve the luminescence of Mn4+ and the related mechanisms are deeply studied. Ultimately, a far-red light emitting diode lamp is fabricated by exciting a far red phosphor Sr9Y2(WO6)(4): 0.0025Mn(4+), 0.01Mg(2+) using a 365 nm n-UV illuminating LED chip. Our studies have shown that Sr9Y2(WO6)(4): Mn4+, Mg2+ phosphors have potential application in controlling or adjusting plant growth in plant-lighting.