The Research Of The Synthesis Of Upconverting NaYF₄:Yb³⁺，Er³⁺ Nanocrystal And Its Luminescence Property

Rare earth doped upconversion luminescence nanocrystals have drawn greatattention due to its unique optical properties. Rare-earth-doped upconvertingmaterials have wide potential applications in many fields, including phosphors,display monitor, lasers, amplify for fiber-optic communications and especially inbiology/biomedicine. Compared with other fluorescent materials, such as organicdye, the upconverting materials have several advantages such as narrow bandemissions, high photostability, low background light, nonfading, and no significantinfluence of environment under near infrared radiation; thereby they can be used asbiological label materials.Different methods were employed to prepare NaYF4: Yb, Er nanoparticles andthe luminescence properties of the final products were also investigated.1. The ionothermal approach was employed to synthesize upconversionnano-/submicrocrystals （UC-NMCs） with diverse morphologies and sizes,which could be controlled by synthetical parameters, like imidazolium cations,cosolvents, Ln³⁺ and fluoride concentrations, as well as ionothermal time. Basedon the experimental data of these parameters, the possible mechanism of the nucleation and growth of UC-NMCs in the IL is discussed.2. Homogeneous NaYF₄core/shell nanoparticles were successfullyprepared. The upconversion emission was increased by using this structure. Onthe other hand, based on the obtained core/shell structure, we furtherinvestigated the quenching property of the Yb³⁺ doped in the shell.