Synthesis And Photoluminescence Properties Of Rare Earth Doped Phosphate And Fluoride Nanoparticles Prepared In A Microreactor Systerm

In the field of fluorescent biological labeling,semiconductor nanocrystals have heavy metallic toxicity and fluorescent light flashing,so rare earth doped luminous nanoparticles have attracted many attentions.However,little reliable method,which can prepare redispersible rare earth doped nanoparticles with narrow particle size distribution and high luminescent properties at the present time was reported.Recently microreaction technology is expected to have a number of advantages for synthesis of nanoparticles,such as feasibility for controlling the experimental condition exactly, possibility for optimizing reaction parameter fastly,and scale up easily.Microreactor technology has shown the application value for preparing nanoparticles. In this paper,current study on luminescence nano-materials used for biological labeling,the rare earth doped materials and the microreactor technology had been reviewed.The luminescence mechanics,the preparation methods of rare earth materials were introduced.The parameters of microreactor,such as the mixing of microfluids,the mass transfer between microfluids and the heat transfer of microfluids had been studied.The microreactor which can rapidly mix two kinds of reaction microfluids and effectively controlled the reaction time had been made up.The CePO₄:Tb,LaPO₄:Eu,LaPO₄:Ce,Tb nanocrystals were prepared in ethylene alcohol by a microreactor,and their phase structure,morphology and fuorescence property were characterized by X-ray diffraction spectra(XRD),transmission electron microscope(TEM)and photoluminescence(PL).The results of XRD indicate that nanoparticles crystallized well with a hexagonal structure.The TEM images illustrate that the LaPO₄:Ce,Tb nanoparticles prepared in a microreactor with 5s reaction time had the main diameter of below 20nm and were well dispersible.The results of PL indicate that Ce_0.70PO₄:Tb_0.30,La_0.90PO₄:Eu_0.10, La_0.70PO₄:Ce_0.20,Tb_0.10nanoparticles with high fluorescent properties can be prepared in a microreactor with low reaction temperature of 80℃and short reaction time of 20s,and the quantum yields of these nanoparticles can reach 22%,25%,24%respectively.In order to improve the product rate of nanoparticles prepared in a microreactor, two kind of heating methods microwave and oil bath were used to prepare nanoparticles.The results illustrate that microwave obviously improve the productive rate which can achieve more than 90%.The CeF₃:Tb,LaF₃:Ce,Tb nanocrystals were prepared in ethylene alcohol by a microreactor,and their phase structure, morphology and fluorescence property were characterized by X-ray diffraction spectra(XRD),transmission electron microscope(TEM) and photoluminescence(PL).The results of XRD indicate that nanoparticles crystallized well with a hexagonal structure.The TEM images illustrate that nanoparticles are nearly spherical with diameter of 5-10nm,and have homogeneous size distribution,well dispersibility.The results of PL indicate that Ce_0.80F₃:Tb_0.20 nanoparticles with high fluorescent property can be prepared in a microreactor with low reaction temperature of 80℃and short reaction time of 20s,and the quantum yield of nanoparticles can reach 32%.The results of a simple fluorescent labeling indicate that the most rare earth luminous nanoparticles(Ce_0.80F₃:Tb_0.20)can come into lung cell.The luminous nanoparticles can be distinctly seen under the fluorescent microscope.Above results show that rare earth doped nanoparticles in a microreactor have the possibility for using in the field of biological labeling.