Synthesis And Properties Of Rare-earth Metal Doped Semicondutor Nanocrystals And Full-color Emitting Phosphors

The full-color emitting Zn2SiO4:Ti, Mn, Eu phosphors, red-emitting SnO2:Eu3+and ZnO:Eu3+ nanocrystals were prepared by hydrothermal method. The phosphor crystal structures were analysised by X-ray diffraction (XRD) and their optical properties were studied by PL.The crystal structures of the Zn2SiO4:Ti, Mn, Eu phosphors prepared by hydrothermal method with different conditions show the same pure Zn2SiO4 structure. The excitation spectra of Zn2-xSiO4:x Mn are consist of an intense charage transfer band and host absorption. The PL spectra, excited at 247 nm, are consist of the 4T1-6A1 emission transitions of Mn2+. The PL intensities of the phosphors are dependent on Mn2+ concentration and quenched for the Mn2+concentration of 3.0 at.%. The excitation spectra of Zn2-xSiO4:x Ti4+ is consist of an intense O2--Ti4+charage transfer band and the PL spectra , excited at 220 nm, are consist of the 2E-1T emissions of Ti4+. Their PL intensity are dependent on Ti4+ concentration and quenched for the Ti4+concentration of 2.5 at.%. The white light-emitting phosphors obtained by codoping Ti, Mn and Eu in Zn2SiO4.SnO2:Eu3+ nanophosphors were prepared by hydrothermal method. XRD analysis showed the formation of pure tetragonal rutile crystalline phase of tin oxide. Some samples were sintered at different temperatures. The sizes of SnO2:Eu3+ nanocrystals grew bigger when heat treatment temperature increased. The PL intensities of SnO2:Eu3+ nanocrystal are reduced by the heat treatment. The excitation spectra of SnO2:Eu3+ nanocrystal are consist of f-f transitions of Eu3+.ZnO:Eu3+ nanophosphors were prepared by hydrothermal method. XRD analysis showed the formation of pure wurtzite crystalline phase of zinc oxide. The ZnO:Eu3+ nanocrystals with the different sizes can be obtained by controlling Zn2+ concentration. we found that the smaller the size of the ZnO:Eu3+ nanophosphor the stronger the light emission. The PL intensities of the ZnO:Eu3+ nanophosphors decrease significantly with the heat treatment. There is the red shift of emission peak at 699nm after the heat treatment.