Preparation And Luminescent Properties Of Nano-v-based Rare Earth Luminescent Materials

Because of the effect of the small size ,quantum size and big ratio surface , nanosized materials have a lot of different behaviors from the bulk materials , such as luminescence ,heat and electromagnetics etc . Especially following the development and application of the rare-earth luminescent materials ,searching a kind of new materials –naosized rare-earth luminescent materials are becoming more and more important and one of hotspots in investigation .This paper searched the methods and conditions of preparing nanosized rare-earth luminescent materials . At last , the method of chelate sol-gel is used and a series of nanosized YVO4:Ln are prepared with the condition of starch as a complexant , at 50℃ water bath and roasting at 700℃ for 10~15minutes. The size of nanosized powder is under 100nm and the lest size is 14.3nm . As a result , the method of chelate sol-gel is a better way to prepare nanosized rare-earth luminescent materials .A great deal of improvement and breakthrough has been done in this aspect . The method of preparing nanosized luminescent materials and the condition of expriment have also been improved . Especially the calcinating temperature and the complexant are very better . Large molecule starch is used as complexant , solubitity complex compounds are prepared which reduced free ions in the intermediate compounds . Stabling complex reduce the difference of the ion . Metal ions are freezed at polymer network to keep primitive ratio . At the same time , large complexant have many ligands , which make ligand and metal ion have strong acting force . In addition , mechanical damping of large molecule chain prohibit nanosized crystal from agglomerating .To establish the different effecting on structure and behaviors , some bulk materials of YVO4:Ln (Ln=Eu ,Dy ,Sm ,Tm ) are prepared by solid reation . The spectral difference between nanosized and bulk YVO4:Ln was studied by X-ray powder diffraction(XRD), Fourier transform(FT-IR) spectroscopy ,luminescence spectra, and the distribution of nanosized particles. The experiment results showed that the blue shift of IR bands is obviously observed , the relative fluorescence intensity enhanced and X-ray powder diffraction bands are broadened with the particle size reducing.In order to study the property of Tb3+ ,nanosized YPO4:Tb is prepared by the method of coprecipitation . And also , GdVO4:Eu and LaVO4:Eu are prepared and compared with the fluorescence spectroscopy of YVO4:Eu .In the end , Ca3(VO4)2 :Euå'ŒSr3(VO4)2: Eu are prepared by the method of sol-gel autogeneous combustion and also compared with the fluorescence spectroscopy of YVO4:Eu . The results show that the fluorescence intensity of YVO4:Eu is the strongest . So YVO4 is a better substrate of rare-earth doped nanosized luminescent materials.