Synthesis of near-white emission phosphors for luminescence lifetime thermometers and flexible security films

Novel near-white emission phosphors of single Pr3+-doped Ca2(Gd,Y)TaO6 double perovskites were successfully prepared. Their crystal structures, morphologies, elemental compositions, photoluminescence (PL) behaviors, internal quantum yields, thermal stabilities, etc. were systemically investigated. Interestingly, the chemical composition of Gd3+ ions replaced by Y3+ ions did not affect the crystal structure of the monoclinic structure in the P 21/n(14) space group. Particularly, the PL emission spectrum of the optimal Ca2YTaO6:Pr3+ phosphors showed different dominant peaks compared to the Ca2GdTaO6:Pr3+ phosphors due to the appearance of cross-relaxation. Note that the near-white region chromaticity coordinates/internal quantum yields of the optimal Ca2GdTaO6:Pr3+ and Ca2YTaO6:Pr3+ phosphors were (0.363, 0.438)/28.1 % and (0.350, 0.441)/27.4 %, respectively. Finally, the potential applications of single Pr3+-doped double-perovskite phosphors were expanded to luminescence lifetime thermometers and flexible safety film applications.