Preparation And Properties Of Rare-earth Doped Yag Nanocrystalline Powders

As the increasing development in rare earth doped Yttrium Aluminum Garnet (YAG), especially the application of the YAG:Er3+ nanoparticles in the field of mid-infrared wavelength Lasers and the YAG:Ce3+ as yellow fluorescence powders in the power White-LEDs. Thus, the study on the rare-earth-doped YAG has been the main research direction of the illuminant materials in our society.The dissertation mainly focused on the study of the synthesis and characterizaiton of YAG:Er3+ and YAG:Ce3+ nanoparticles with advanced Pechini method. As starting materials, the nitrate compound and ammonium citrate, were dissolved in deioned water, and mixed solution was added in, which was composed of acrylamide, and N,N,- Methylene-bis-acrylamide, as cross linkers. Magnetic stirring is performed to obtain uniform solution. Then, a small quantity of AIBN in acetone, was added to the uniform solution as a initiator,and mixed homogeneously by stirring, the mixed solution was heated at 90oC in water bath, and then acrylamide and the corss liker polymerized to form gel with the structure of three-dimensional space network, the precursor was then calcined at 1000 oC-1200 oC for about 3 hours to obtain the rare earth doped YAG nanoparticles. The doped Yttrium Aluminum Garnet nanoparticles that were synthesis with this method characteriazed by not only lower YAG crystalline phase-changing temperature(880oC) but also sharp of near globular and uniform size of particles(crystalline of 10-30nm in diameter).The optimized parameters was adopted in our experiment as follows:: the overall molar ratio of the metal ions and chelating agents was 1:1, the PH value of reaction solution was 5, the quality ratio of acrylamide and N-N 'methylene double was 6:1 and the temperature of water bath box was 90 oC.In the preparation of Ce doped YAG, the effect of Ce concentration as represented by (YxCe1-x)3Al5O12 on the optical characteristics of Ce: YAG powder had been studied in detail, the samples with different x value i.e. x=0.02, 0.04, 0.06, 0.08, 0.1 respectively were synthesized and analysised. The results showed that the luminous efficiency of Ce3+ :YAG nanoparticles reached its maximum at x=0.06 in our experiment.The XRD results also identified that with the concentrationg fo Ce below the 10at% the obtained material in our experiment was of YAG crystalline phase.In the Er doped YAG preparation, the materials with x=0.01, 0.05, 0.09 as in (YxEr1-x)3Al5O12 formula was synthesised. The spectra measurement of the YAG:Er3+ nanoparticles showed that the abundant spectral components have been observed in the its absorbing and emitting spectrum.It showed that the advanced Pechini method was an effective way for the preparation of rare-earth doped YAG nanoparticles. As the rare earth doped YAG has been increasingly widely applied in modern industry and scientic researchs, the work presented in this dissertation can be some kind of meaning to the following researcher.