Preparation of Eu^(2+),Dy^(3+),Zr^(4+)ions co-doped strontium aluminate/molybdate multi-optical functional hybrid pigments for anti-counterfeiting

Eu^(2+),Dy^(3+)and Zr_(4+)ions co-doped strontium aluminate(i.e.,SrAl_(2)O_(4):Eu^(2+),Dy^(3+),Zr_(4+))/molybdate(i.e.,Ho2MoO6or Nd2MoO6)with photo-/mechano-luminescence and allochroic effect as multi-optical functional hybrid pigments were prepared via solid state reactions and subsequent mixing.The phosphor and hybrid pigments were characterized by X-ray diffraction,scanning electron microscopy with energy dispersive X-ray spectroscopy,ultraviolet-visible spectroscopy,L*a*b*color scale analysis,spectrophotometry and mechanoluminescent measurement.The results show that the optimum luminescent emission intensity of SrAl_(2)O_(4):Eu^(2+),Dy^(3+),Zr_(4+)phosphor can be obtained when 5 mol%Zr_(4+)ions is doped into the lattice.Under the excitation of 365 nm wavelength,the hybrid pigments prepared with the phosphor and molybdate at a mass ratio of 1:1 present a green broad band emission located at 460-650 nm due to 4f65d1→4f7transitions of Eu^(2+)ions.The hybrid pigments have the superior mechanoluminescent property and emit light after being exerted by mechanical stresses.Besides,the hybrid pigments also exhibit an allochroic effect under different illuminants.In addition,the anti-counterfeiting of the hybrid pigments as a promising application was also presented.