Self-Assemble Preparation And Functionalization Of Micro/Nano-Upconverting Luminescent Materials

Rare-earth doped nanocrystals have broad application prospects in catalysis, optoelectronics and biological labeling fields etc due to the advantages in the nanocrystals such as high quantum yield, good light stability and tunable wavelength of excitation light. The synthesis and surface functionalized modification of rare-earth doped upconverting luminescent materials were studied systematically. The main contains of this paper involves the following aspects:1. YF3:Yb, Er and NaYF4:Yb, Er nano-particles were synthesized successfully by microemulsion method in the CTAB/n-butyl alcohol/n-octane system. YF3was transformed to NaYF4by simply adjusting the addition amount of F-(NH4F).2. NaYF4:Yb, Ho and NaYF4:Yb, Ho@Au nanoparticles were synthesized by microemulsion method. The experimental condition of this method was mild and the process was quick. The assemblies of upconverting particles and Au nano-particles were achieved simply at room temperature. Results of XRD and HRTEM showed that the crystalline phases of NaYF4and Au existed simultaneously. There was a characteristic peak of Au in UV-vis absorption spectrum at546nm. Upconverting luminescent intensity of the composite material was enhanced obviously compared with the nanoparticles before coating.3. α-NaYF4:Yb, Tm with high luminescent intensity was prepared by citric acid assisted hydrothermal method. The influences of the amount of citric acid, hydrothermal temperature on crystalline phase, morphology and luminescent property were studied. The characterization results showed that the crystallinity was optimum when the amount of citric acid was8mmol, temperature was180℃and hydrothermal time was24h. Sizes and morphologies of the particles were studied by changing hydrothermal temperature. And luminescent properties were changed by adjusting the amount of citric acid.4. NaYF4:Yb, Er with small particle size, high luminescent intensity and different crystalline phases were synthesized by hydrothermal method using DL-2-Octanol as surfactant. Materials with different morphologies were achieved by adjusting hydrothermal temperature and time. Surfaces of the products were modified by SiO2which improved the water-solubility and biocompatiblity of particles and the thickness of homogeneous SiO2shell was about5nm.