Warm white-light generation in Ca9MgNa(PO4)7:Sr2+, Mn2+, Ln (Ln=Eu2+, Yb3+, Er3+, Ho3+, and Tm3+) under near-ultraviolet and near-infrared excitation

Abstract To obtain warm white-light emission, a series of Ca 9 MgNa(PO 4 ) 7 :Sr 2+ , Mn 2+ , Ln (Ln=Eu 2+ , Yb 3+ , Er 3+ , Ho 3+ , and Tm 3+ ) phosphors were designed and their photoluminescence properties under near-ultraviolet and near-infrared excitation were studied. For near-ultraviolet excitation, blue-white emission is produced initially in the Eu 2+ single-doped Ca 9 MgNa(PO 4 ) 7 , whose excitation band can well match with the near ultraviolet LED chip. By introducing Sr 2+ ions into Ca 9 MgNa(PO 4 ) 7 :Eu 2+ , the Eu 2+ emission band beyond 500 nm is enhanced obviously. Correspondingly, the emitting light color is tuned to nearly white. To generate warm white light further, Mn 2+ is doped into the Ca 8.055 MgNa(PO 4 ) 7 :0.045Eu 2+ , 0.9Sr 2+ and the correlated color temperature is decreased largely. For near-infrared excitation, the green, red, and blue emissions have been obtained in the Yb 3+ -Er 3+ , Yb 3+ -Er 3+ , and Yb 3+ -Er 3+ co-doped Ca 9 MgNa(PO 4 ) 7 phosphors, respectively. And warm white light is also produced in the Ca 9 MgNa(PO 4 ) 7 :Yb 3+ , Er 3+ , Ho 3+ , Tm 3+ under 980 nm excitation.