Synthesis And Surface Modification Of Rare Earth Fluoride Fluorescent Nanoparticles

Compared with traditional fluorescence probe, rare earth fluoride fluorescent nanoparticles have the advantages of large Stokes shift, high fluorescence emission intensity, long fluorescence lifetime, steady chemistry property, nontoxic and so on. In this paper, the synthesis and surface modification of rare earth fluoride fluorescent nanoparticles were studied, and the synthesized products were characterized.LaF3:Eu fluorescent nanoparticles were synthesized aqueously. Effect on the product property was inspected. And the fluorescent nanoparticles were characterized by fluorometer, IR and XRD. Based on this, NaGdF4:Eu fluorescent nanoparticles were synthesized by a gentle method. At the same time, effect on the product property was inspected. And the fluorescent nanoparticles were characterized by XRD and TEM. Finally, the surface of NaGdF4:Eu fluorescent nanoparticles was modified with SiO2.The experimental results indicated that the optimum conditions of synthesis of LaF3:Eu fluorescent nanoparticles were as follows:reaction temperature of 75℃; reaction time of 2 h; total concentration of rare earth ion (La3+ and Eu3+) of 0.05 mol/L; solution pH of 10.0; Eu3+ doped content (the doped content is the rate of Eu3+mol in the total mol of rare earth ion)of 30%; the mol ratio of total content of rare earth ion, citrate and NaF of 4:5:9. The XRD and IR characterization results showed that LaF3:Eu fluorescent nanoparticles synthesized by the method had good crystallization, whose average particle size was 7.7 nm, and whose surface was modified with citric acid.The experimental results indicated that the optimum conditions for synthesis of NaGdF4:Eu fluorescent nanoparticles were as follows:reaction time of 2 h; total concentration of rare earth ion (Gd3+ and Eu3+) of 0.05 mol/L; Eu3+ doped content of 30%. The XRD and TEM characterization results showed that the crystallization was good, and the average particle size was 10 nm.The surface of NaGdF4:Eu fluorescence nanoparticles was modified with SiO2. The optimum conditions for surface modification were as follows:the solvent of anhydrous alcohol, and reaction time of 1 h. The size distribution and IR characterization indicated that NaGdF4:Eu fluorescent nanoparticles had been modified with SiO2 successfully.