Sol - Nano TiO ₂ The Optical Properties Of Gel Method Sm ^{3 + , Eu 3 + Doping}

Rare earth doped semiconductor material is a new kind of luminescent materials which has intensive application prospect in various kinds of domains such as optoelectronic devices, solid-state laser material, flat panel display, high-energy radiation detector, medical diagnosis, etc, so it has aroused more and more attention over the recent years. In previous study, many broadband gap semiconductors were studied as matrix materials to effectively stimulate the rare earth ions and generate strong luminescence, such as GaN, Y2O3, TiO2, Gd2O3, etc. In all of these, TiO2is a kind of important broadband gap semiconductor materials owing to its excellent optical performance such as the strong ultraviolet absorption capacity, photosensitive, air-sensitive and pressure-sensitive etc, so it has been widely used in the automotive industry, sunscreen cosmetics, wastewater treatment, air purification, environmental protection. However, as the research continued, the researchers found that TiO2has some shortcomings which impedeit to be a excellent material for optoelectronic devices due to its structure, such as broad-band gap; lower utilization of solar energy and luminous efficiency; hard to disperse and recycle etc. In order to overcome these shortcomings, earth elements were successes doped in tonano TiO2to improve and adjust the performance of the materials by researchers. It was found that rare earth doped TiO2nanoparticles materials showing efficient luminescence property which has broad application prospect in sensitive element, photocatalyst, solar cells, etc. Thus it can be seen that the combination of rare earth and TiO2nanomaterials is a promising research area. In this thesis, Nanometer TiO2was selected as matrix materials, Sm3+, Eu3+single-doped TiO2nanomaterials and Sm3+, Eu3+co-doped TiO2nanomaterials were prepared successfully by sol-gel method. The structures of Sm3+, Eu3+doped TiO2nanocrystalline were characterized by using X-ray diffraction (XRD); Raman; X-ray photoelectron diffraction (XPS), ultraviolet-visible-near infrared spectrophotometer (UV-Vis) and fluorescence spectrophotometer. The luminescence properties and luminescence mechanism of Sm3+, Eu3+doped TiO2nanocrystals were studied by Light luminescence excitation spectra (PLE) and optical emission spectra (PL).In introduction, firstly the basic properties of TiO2nanometer, rare earth luminescence mechanism and advantages has been described, and then the development of rare earth doped TiO2nanoparticles, its applications and preparation methods has been described, Further more the problems of present research has been expounded basing on the research status of rare earth doped TiO2nanoparticles. Lastly, the experiment content, purpose and meaning of Sm3+, Eu3+doped TiO2nanometer luminescent samples has been described.In Chapter2, an introduction of experiment research purpose and research methods for Sm3+, Eu3+doped TiO2samples. The experimental method consisted of specification of materials, sample preparation and characterization of methods in this thesis.In Chapter3, TiO2:Sm3+nanocrystalline was prepared success fully by sol-gel method. The samples occurred580nm,613nm,666nm and730nm four emission peaks under the excitation of350nm, it corresponded to the4G5/2→6H5/2、4G5/2→6H7/2、4G5/2→6H9/2、4G5/2→6H11/2energy level transition of Sm3+ion and the luminous intensity of613nm (4G5/2→6H7/2) transition was the strongest. It was found that the optimal doping concentration was1.0mol%of Sm3+ion under heat treatment at550℃. At the same time, we discussed the effect of phase change on the luminescence properties of the TiO2samples. It had a significant impact bewteen luminescence and transformation of Anatase phase into rutile. The luminescence decreased with rutile phase content increased. This was because the Sm ions doped, the defect energy levels located different place in the two phase.In Chapter4, TiO2:Eu3+nanocrystalline was prepared successfully by sol-gel method. The luminescent properties and luminescence mechanism of samples has been investigated. It was found that TiO2:Eu3+nanocrystalline samples can produce strong red emission. The Eu3+ions mainly located at the asymmetrical center in TiO2nanocrystals. In addition the luminous intensity increased with the increase of doping concentration, the luminous intensity was strongest when Eu3+ion concentration reacheed1mol%and luminous intensity weaken when the concentration was higher than1mol%. Furthermore we studied the influence of the heat treatment temperature on the TiO2:Eu3+nanocrystalline sample luminescence, the best heat treatment temperature was650℃.In Chapter5, TiO2:Sm3+, Eu3+nanocrystalline samples was prepared successfully by sol-gel method on the basis of the first two chapters of the experiment. Excitation spectra and emission spectra of TiO2:Sm3+, Eu3+samples has been got by changed Eu3+concentration with fixed Sm3+concentration. The energy transfer process from Sm3+ion to Eu3+ion has been studied. The optimal doping composition was TiO2:1%Eu3+,0.8%Sm3+.In Chapter6, the main research results were summarized, in addition, the existed problems and the further research direction were also pointed out.