The VUV–vis luminescent properties of NaYFPO4: Dy3+ phosphor

Dy3+-doped monoclinic NaYFPO4 phosphor has been synthesized by solid-state reaction technique. Its photoluminescence in the vacuum ultraviolet (VUV)-visible region was investigated. The most intensity broadband emission centered at about 171 nm was the host-related absorption. Another broadband at 153 nm could be related to the O2→Dy3+ charge transfer band (CTB) absorption. The excitation peaks located at 178 nm and 256 nm were the spin-allowed (SA) and spin-forbidden (SF) f–d transitions of Dy3+, respectively. Some sharp lines in the range of 280–500 nm were due to the f–f transitions of Dy3+ within its 4f9 configuration. Under the VUV–vis excitation, the Dy3+-doped NaYFPO4 phosphor showed the characteristic emissions of Dy3+ (4F9/2→6H15/2 transitions and 4F9/2→6H13/2 transitions) with a stronger blue emission peaking at about 485 nm. All the chromaticity coordinates of the sample were in the near cold-white region. It can be predicted that this phosphor can be applied in both mercury-free luminescence lamps and white LED.