The phosphors that are able to convert vacuum ultraviolet(VUV)light into visible light are demanded for the development of novel displaying and lighting devices.NaYF4:Pr3+,Dy3+,NaGdF4:Pr3+,NaGdF4:Dy3+and NaGdF4:Pr3+,Dy3+were prepared by hydrothermal synthesis method and their luminescent properties in VUV-vis spectral region were investigated at room temperature.For NaYF4:Pr3+,Dy3+,no energy transfer process from Pr3+to Dy3+was observed.However,the introduction of Gd3+into the fluoride lattice led to intense Dy3+emissions upon Pr3+4f5d state excitation.Gd3+acted as an intermediate,resulting in efficient energy transfer from Pr3+to Dy3+in NaGdF4.Pr3+transferred most of its energy to Gd3+,and then the energy was transferred from Gd3+to Dy3+.So NaGdF4:Pr3+,Dy3+not only took full advantage of the intense Pr3+4f5d absorption,but converted the VUV excitation light into the near-white emission of Dy3+.
