Low Temperature Solvent-Thermal Synthesis Of Indium Tin Oxide Nano-particles And Its Upconversion Luminescence

Rare-earth doped luminescent materials have been widely used in phosphors, display monitors, X-ray imaging, scintillators, lasers and amplifies for fiber-optic communications due to their advantages of high absorptive capacity, high conversion efficiency and broader emission range covering from ultraviolet to infrared range. Up-converting luminescence is a unique phenomena observed in rare-earth luminescent materials. When excited with infrared light, rare earth up-converting luminescent nanocrystals can produce visible light with a narrow band width (long life time), stable light emission(less susceptible to environmental impact) and low background. The inorganic nanocrystals have received increasing interests in recent years for their promising application as biomarker. However, the inorganic nanocrystals would produce fluorescence, which can disturb the detection of FD-Fluorescence detection. Therefore, efforts have been made to develop rare earth nanocrystalline upconversion phosphors labeling without background. The nanocrystals of up-conversion phosphors are now in developing stage, the choice of materials and synthesis have been subject to be thorough research. In this paper, we make the systemic discussion of the synthesis of nanocrystalline upconversion phosphors and their luminescence properties.The research of rare-earth luminescence nano-materials were overview in this paper. The preparation methods of nanocrystalline upconversion phosphors and their luminescence mechanism were also summarized. Several methods to improve the efficiency of upconversion and the problems during the research are also discussed.The indium tin oxide (ITO) nanopowders have been prepared by solvothermal process. The effects of solvothermal process parameters on the prepared ITO powders, compose, crystal, granularity, capability were studied, such as solvent, prepared temperature, time, coprecipitate pH, the compactedness of and so on.The results showed that the light blue ITO nanopowders could be obtained at low 190℃for 1 h by using glycol as solvent. SEM and TEM showed the powders were cubic or spherical crystalline with the size of smaller than 100 nm. With the increasing of temperature and adding the PEG 4000 dispersant, the crystallinity and the dispersity of ITO nanopowders were greatly improved.Based on this, the In2O3:Er3+, Yb3+and In2O3:Ho3+, Yb3+ nanocrystalline upconversion phosphors were obtained at low temperature Solvothermal for the first time.The UC spectrums showed that,the crystalline structure of In2O3 were not obviously influenced while codoped with the Er3+/Yb3+ ions or Ho3+/Yb3+ ions. And the obtained nanopowders are good distributive and dispersive. In these codoped systems, the upconversion fluorescence intensity will first increase and then decrease or even cause the fluorescence quenching. All these processes belong to two-photon processes.lt have provided great important prerequisite for the application with the In2O3:Er3+, Yb3+and In2O3:Ho3+, Yb3+ nanocrystalline upconversion phosphors successfully prepared.These indium oxide materials can be made into luminescence thin film, biosensors and nano-probes for biological immune and so on.