Synthesis And Luminescence Properties Of White Phosphors For NUV LED Chips

The luminescent properties of Y2(MoO4)3:Dy3+, Ca2MgSi2O7:Ce3+,Eu2+single host white-light phosphors have been studied in this thesis. It is important for the study of single host white-light phosphors suitable for UV LED chips. The following are the main contents.1.The pure-phase Y2(MoO4)3:Dy3+phosphors were prepared via the solid-state method. It shows that Y2(MoO4)3:Dy3+phosphors have strong f-f excitation peaks in the near ultraviolet(NUV) range by measuring the excitation spectra. It suggests that Y2(MoO4)3:Dy3+phosphors suit for NUV-LED chips. The effect of different Dy3+concentrations to the luminescent properties of Y2(MoO4)3:Dy3+was also analyzed. The optimum concentration for phosphors was obtained as5.0%. Moreover, It showed that the photochromic of phosphors was white under387nm excitation.2.The pure-phase Y2(MoO4)3:Dy3+phosphors were prepared via the sol-gel method. The luminescent properties of the samples were analyzed by measuring excitation and emission spectra of the Y2(MoO4)3:Dy3+phosphors. The optimum concentration (5.0%) for phosphors was obtained. Moreover, the photochromic of phosphors was white-light under387nm excitation. Finally, comparing the two kinds of preparation methods, the phosphors prepared via the sol-gel method have some advantages:smaller particles, more uniform particle size distribution and better white light. In contrast, the phosphors prepared via solid-state method show stronger emission.3.The pure-phase Ca2MgSi2O7:Ce3+,Eu2+phosphors were prepared via the solid-state method, and the luminescent properties of the samples were studied. The energy transfer from Ce3+to Eu2+was demonstrated by analyzing the fluorescence spectra of the Ca2MgSi2O7:Ce3+, Ca2MgSi2O7:Eu2+phosphors. Measuring fluorescence spectra of the Ca2MgSi2O7:Ce3+,Eu2+phosphors, we found that ηT from Ce3+to Eu2+increased with the increasing Eu2+concentration. The energy transfer type from Ce3+to Eu2+was proposed to be electric dipole-dipole by the linear fitting. Moreover, we demonstrate that Ca2MgSi2O7:Ce3+,Eu2+phosphors emit white light under UV light with appropriate Ce3+ and Eu2+concentrations.