Preparation And Optical Properties Of Rare Earth And Dye Doped SiO₂ Nanoparticles

Recently, Eu3+, Tb3+ and Rhodamine B (RhB) doped SiO2 nanoparticles have been of great interests due to their applications in bioconnectors, biomedicines, fluorescent labelings and microsensors. As the development of nanotechnology, Eu3+, Tb3+ and Rhodamine B (RhB) doped SiO2 nanoparticles have become new hotspots in fluorescent enhancement materials, especially in the area of bioinstrumentations and biomedicines as biological labels. Eu3+, Tb3+ and Rhodamine B (RhB) doped SiO2 nanoparticles were prepared, and their morphology, element and optical properties were characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), UV-Vis-NIR spectrophotometer and RF-5301/pc fluorescence spectroscopy, which as follow:The Eu3+, Tb3+ doped SiO2 nanoparticles were prepared by the improved alkaline catalytic method. TEM results showed that the nanoparticles were uniform in size distribution and had a good monodispersity. UV-Vis-NIR results showed that there was a strong absorption peak which was corresponding to f→f electron transition of Eu3+ in the visible light range. XRD results showed that there was a wide diffraction peak in the vicinity of 20= 22.15°. SiO2 nanoparticles became amorphous while the annealing temperature was below 1000℃; when the annealing temperature was or above 1000℃, it could be clearly observed a number of sharp peaks, SiO2 were changed from amorphous to crystalline structure. RF-5301/pc results showed that the emission peaks of Eu3+ and Tb3+doped SiO2 nanoparticles varied with the different Eu3+ and Tb3+ doping concentrations. When the samples were annealed from 200 to 1200℃, they were changed to crystalline from amorphous, however, the positions of the emission peaks were almost remained the same, their emission spectra were influenced strongly by the material structure, and the emission peak value reached a maximum at 800℃.RhB doped SiO2 nanoparticles were prepared by the Stober method and the redox reaction, silver nanoparticles were grown on the surface of RhB doped SiO2. UV-Vis-NIR results showed that the plasma absorbance spectra became broader and stronger with the silver shell growth; however, the absorbance peaks did not have obvious shifting. RF-5301/PC results showed that SiO2 provided the suitable interval between RhB and silver shells in RhB doped SiO2 nanoparticles. The growth of the silver shells could also enhance the local electromagnetic field around them which could enhance the RhB fluorescence.