Red shift properties, crystal field theory and nephelauxetic effect on Mn4+-doped SrMgAl10-yGayO17 red phosphor for plant growth LED light

The discovery of novel Mn 4+ -doped oxide red phosphor with suitable spectrum for plant growth is a hot issue in the recent years due to the characteristic red photoluminescence of 2 E g  →  4 A 2 transition in Mn 4+ ions. Generally, the emission position of Mn 4+ is hard to tune because of specific crystal field in most phosphors. In this work, tunable luminescence property with obvious red shift in the spectra is observed in the Mn 4+ -doped SrMgAl 10-y Ga y O 17 red phosphor via simple substitution of Ga 3+ for Al 3+ , and crystal field theory and nephelauxetic effect are employed to explain this phenomenon. Meanwhile, the Ga 3+ dopant changes the shape of the spectra because Ga 3+ dopant guides the replacement site of Mn 4+ and changes the luminescence center. Improved emission intensity is obtained because appropriate Ga 3+ doping leads to larger band gap and reduces non-radiative transitions. Phosphor-converted LED (pc-LED) devices fabricated with blue chip (470 nm) and the as-obtained SrMgAl 10-y Ga y O 17 :1.0%Mn 4+ phosphors emit bright blue and red light, which fit the absorption regions of plant pigments well, thus SrMgAl 10-y Ga y O 17 :Mn 4+ phosphor can be a candidate for plant growth LED light.