Study On Preparation And Luminescent Of Nanocrystal Sodium Yttrium Fluoride Co-doped With Rare-Earth Ions

For unipue luminescence and surface properties of the upconversion fluorescent materials,these nanoparticles may find great applications in the fields of color displays, biolabels,light-emitting diodes(LEDs),optical storage,opeoelectronics,and solid-state lasers.Recently,nonosized fluorescent labeling materials have been widely used for biological studies and clinical applications.As bio-molecule fluorescent labeling material,nanopartieles with small diameter,uniform distribution and strong luminescent intensity are necessary.Upconverting transfer efficiency lies on phonon energy.To overcome the phonon decay problem,it is necessary to choose a lattice that has much lower phonon energy.NaYF₄ is suitable matrices with high chemical stabilization and very high transfer efficiency.NaYF₄ has been reported as the most efficient host material for Yb/Er(or Yb/Tm,Yb/Ho)co-doped IR-to-visible upconversion phosphors.Highly purity NaYF₄:Yb³⁺,Er³⁺ nanoparticles are successfully prepared in large quantities using oil state approach assisted by a the chelating agent and stabilizer, Polyvinylpyrrolidone(PVP).The lanthanide ions were complexed with the pyrrolidone groups of PVP and then released slowly to the solution to react with fluoride ions.A facile wet chemical synthesis method(hydrothermal method) was used to prepare rare-earth(Yb³⁺,Er³⁺,Ho³⁺,Tm³⁺) doped NaYF₄.In wet chemical routes to produce lanthanide-doped luminescent nanoparticles,organic ligands were usually repuired to control the particle growth in order to get products in the nonometer scale. Being covered with oleic acids,couldalsoserveasa stabilizer of the nanocrystals.In this paper,it is given a presentation of the synthesis process and the upconverting mechanism of the upconversion fluorescent materials.On the basis,the oil state method and hydrothermal method were used to prepare rare-earth doped NaYF₄. The main contents and results are as following:This article studied the NaYF₄ upconverting materials was prepared by using facile methods,while studying their property and the upconverting mechanism.The as-obtained products were characterized by means of X-ray diffraction(XRD), transmission electron microscopy(TEM),Fourier transform infrared spectroscopy (FTIR) and photoluminescence spectroscopy(PL) etc.The up-conversion spectrum was measured by Hitachi F-4500 spectrohphotometer,under 980nm diode laser excitation. The impact of different concentration of rare-earth ions on the upconversion luminexcence intensity was discussed.The relationship between upconversion relative intensity and pump power was also studied.