Self-Assemble Preparation And Spectral Properties Study Of Micro/Nano-Luminescent Materials

In this thesis, the synthesis of rare earth ions doped fluoride, the choice of composite materials, the preparation of the CdS quantum dots were systematacially studied, and the concrete contents are as follows:In CTAB/n-octane microemulsion system, NaYF4:Yb, Er/Ho/(Er, Tm) nanoparticles were successfully synthesised under room temperature. The experimental method was mild, quick, and with a high rate of repetition. The crystallinity of material was good and the luminescent properties of samples were stable.In this microemulsion system, CdS quantum dots could be rapidly synthesised by adjusting pH value of the system. A series of characterization indicated that the size of CdS quantum dots was about4.6nm. With increasing the reaction time, the size of CdS quantum dots turned to be bigger. Meanwhile red shift could be observed in the UV-vis absorption spectrum pattern. NaYF4:Yb, Er/Ho@CdS core/shell composite material was prepared by adding NaYF4:Yb, Er/Ho nanoparticles into the microemulsion system containing CdS quantum dots. The upconversion luminescent intensity of the composite material had an obvious enhancement compared with the core. But the emission peak positions were unchanged. The strengthened luminescent mechanism was still under exploring.In addition, rare earth fluoride@CdS@SiO2composite material was further synthesised by using the microemulsion method. The thickness of SiO2shell was about40nm. Mouse myeloma cells(SP2/0) were breeded with this composite material. The influences of composite material on livability of SP2/0were detected by cell colorimetric method (MTT method). After culturing48hours, cells were still viable. After72hours, there was less than90%of the survival rate of SP2/0. SP2/0doped with composite material after48hours could emit red emission centered at670nm when excitated by550nm laser. With the concentration of nanoparticles increasing, the luminescent intensity was enhanced. This result provided evidence for the further application of NaYF4:Yb,Er/Ho@CdS@SiO2composite material in biological field.NaYF4:Yb, Eu (â…¡) microparticles with blue emission were successfully prepared by solvothermal method with sodium citrate as the reducing agent. The samples were about5μm in size with hollow morphology, and the thickness of their walls was about1μm.Through the photoluminescent spectroscopy testing, the luminous peak located at430nm when excited by365nm laser, which was attributad to the4f7â†'4f65d1transition of Eu (â…¡). It was found that the luminescent intensity was enhanced by adding Yb ions. When the molar ratio of Yb to Eu was3:7, luminescent intensity reached to the maximum.