Preparation And Optical Properties Of Yb-doped Y₂O₃Nano Functional Materials

Yb³⁺-doped excitation is a new candidate for high power,short-pulse laser,whichhas good laser properties such as large wide absorption and fluorescent band, longlifetime,high thermal conductivity. At present, research reports of excitation arealmost YAG as host material.However, the research of Yb³⁺:Y₂O₃is seldom reported.In this thesis,Y₂O₃with low phonon energy was selected as host material.Preparation and fluorescent property of the Yb³⁺-doped nanomaterials have beeninvestigated. The research section contains three subunits. Main contents of the thesisare summarized as follows:1. Obtaining nanopowders with uniform size and good dispersion, the liquid phaseco-deposited method was adored to prepare the Yb³⁺:Y₂O₃nanopowders. Theinfluence factors, including pH value, reaction temperature, calcination temperature,dripping speed and Yb³⁺-doped concentration, size and property of the nano-particleswere systematically studied．Nanopowders which produce via precipitation usingammonia water as precipitant are in the range of50～100nm,pH is8～9;Usingammonium hydrogen carbonate as the precipitant,nanopowders with different size（40～80nm） were obtained.optimal reaction parameters were precipitant concentration（1mol/l）, dripping speed（1ml/min）, pH value（8）, calcination temperature（1000℃）.2. The luminescent properties of nanopowderss for different dopingconcentrations （from1mol%to20mol%） were investigated. The fluorescencequenching concentration is10mol%, while the fluorescence lifetime decreased as theconcentration increases. In order to reduce hydroxyl content on nanoparticles surfacewhich affect its fluorescence property of Yb³⁺, the Yb³⁺:Y₂O₃nanopowders underdifferent vacuum were investigated.It has been found that vacuum have a great impacton fluorescent lifetime. From1atm to3×10-2Pa, the fluorescence lifetime increasedas the vacuum increases, the max（1.17ms） has emerged; From3×10-2Pa to8× 10-4Pa,the lifetime decreased to191μs.Therefore, it is an effective way to reducehydroxyl content and improve the fluorescence efficiency; nanopowder was in thehigh vacuum state, the lifetime decreased as vacuum increases, which provide anefficient strategy for nano laser materials.3. Powders sinterability, pore size distribution, grain growth and microstructuralevolution are investigated. Considering the characteristics of pore size distributionand parameters of microstructure, microstructure evolves in an essentially universalmanner depending on the pore size/grain size ratio, but independent of powder size,state of agglomerates, green body density. Further, homogenization of the micro-structural evolution is brought out in the light of the densification coupling with graingrowth. Based on accurate knowledge of the processing of Yb³⁺:Y₂O₃nano-powderand improved understanding of the microstructal evolution and sintering mechanism,the influence of chemical composition of powders, compaction techniques and thesintering schedules on ceramics transmission is evaluated.Based on the absorption andfluorescence spectra, LF theory was applied to calculate the optical parameters.Theresults show that the ceramics has a large emission cross section and long lifetime,indicating it has potential applications in laser.