Preparation Of Rare Earth Doped Aluminate Or Molybdate Long Afterglow Materials And Their Luminescence Properties

Rare earth doped long afterglow nanomaterial, which belongs to a new "green" environmentally friendly material, can absorb the external light source and store up energy. When an external light source is removed, the material can release energy slowly in the form of visible light. Expecially in recent years, the state strengthens the emphasis on energy conservation and environmental protection material, this material has been widely developed and applied to traffic, emergency lighting, anti-fake and other fileds. In this paper, two novel long afterglow materials were prepared via coprecipitation-hydrothermal method, and its structure, morphology, and fluorescence properties were made a systematic study. The main research work was as follows.(1) The Eu, Dy doped strontium aluminate long afterglow materials were obtained by coprecipitation-hydrothermal method. With sigle facter experiments, the effects of doping different concentration of activator and co-activator, the amount of Al(NO3)3 and H3BO3, pH, hydrothermal time, and calcination time on the performances of the samples have been explored. The synthetic conditions were further studied in detail via orthogonal experiment, and the optimal synthetic conditions were with the nEu/nSr as 0.02, the nDy/nEu as 2.5, the hydrothermal time as 8 h and the calcination time as 2.5 h. Then the optimal synthetic conditions were verified by repeated experiment. The results proved that all the resultant samples were mixed crystal phase, which were all composed of SrAl2O4 and Sr4Al14O25. The morphology of the target products was the spherical with about 100 nm diameters. The fluorescence spectra demonstrated the target products emitted strong blue light at 460 nm corresponding to the typical characteristic 4f65d?4f7 electron transition of Eu2+ ions. The afterglow decay curves were substantially the same shape, which were composed of two regimes, the initial rapid-decay and then long lasting phosphorescence afterward, and both had shown a long persistence performance.(2) The Eu, Dy/Nd doped strontium molybdate long afterglow materials were obtained by coprecipitation-hydrothermal method. With sigle facter experiments, the effects of doping different concentration of activator, the coprecipitation temperature, the hydrothermal temperature, pH, and the calcination time on the performances of the samples have been explored. The synthetic conditions were further studied in detail via orthogonal experiment, and the optimal synthetic conditions were with the activator concentration as 25%, coprecipitation temperature as 35 ?, the hydrothermal temperature as 145 ? and the calcination time as 2.5 h. Then the optimal synthetic conditions were verified by repeated experiment. The results proved that all the resultant samples were SrMoO4 crystal phase. The morphology of the target products exhibited the spherical with about 0.5-1 ? m diameters. The fluorescence spectra demonstrated the target products emitted strong red light at 616 nm corresponding to the typical characteristic 5D0?7F2 electron transition of Eu3+ ions. Whilst, the afterglow performance of co-activator Dy3+or Nd3+ions on the target samples were further investigated under optimum conditions. The results showed that all the resultant samples were SrMoO4 crystal phase. The morphology of the samples exhibited the spherical. And the particle size of doping Nd3+ ions in the target products was significantly smaller than the dopant Dy3+ ions, between about 0.1?0.2 ?m diameters. The fluorescence spectra demonstrated all samples emitted strong red light at 616 nm corresponding to the typical characteristic 5D0?7F2 electron transition of Eu3+ ions. The afterglow decay curves were substantially the same shape, which were composed of two regimes, the initial rapid-decay and then long lasting phosphorescence afterward, and both had shown a long persistence performance. The fluorescence and afterglow performance of samples obtained by doping Nd3+ions were superior to the dopant Dy3+ions.