Red/deep-red emitting phosphors of Eu 3+ /Dy 3+ co-doped NaSrGd(WO 4 ) 3 for LED and optical anti-counterfeiting

The family of rare-earth doped phosphors has drawn pronounced attention in technological of fingerprint visualization, anti-counterfeiting, and phosphor-converted light-emitting diodes applications. A series of NaSrGd (1– x – y ) Eu x Dy y (WO 4 ) 3 powder luminescent materials were synthesized by a solid-state reaction. The emission color of NaSrGd(WO 4 ) 3 :Dy 3+ phosphor could be tunned via changing concentrations of Eu 3+ ion. In addition, the phosphors exhibit narrow red-light emission at 610 nm caused by the electric dipole transition 5 D 0 → 7 F 2 of Eu 3+ . Especially, the phosphor exhibits superior thermal stability, its emission intensity of optimum sample remained ± 15% over the temperature range from 233 to 393 K. The Commission International de I’Eclairage (CIE) chromaticity coordinates of x = 0.4 are (0.6388, 0.3371) with a high color purity (92.84%). More importantly, prepared color-changing device of phosphors achieves a high level of optical safety. The results demonstrate that their materials can be potentially applied to the field of white light-emitting diodes (LEDs) and optical anti-counterfeiting.