Study On Nanoscale Rare Earth Y₂O₃: Eu～(3+) Phosphors By Mechanical Solid State Chemistry Reaction

In this paper, preparation and properties of mechanically alloying, solid state reaction, and nano-sized rare earth phosphors are reviewed in details. To counter troubles and limitations of preparing methods of rare earth red phosphors, This paper firstly united mechanically alloying with solid state reaction use to salt-salt reaction system by means of two steps method of preparing precursors and thermal decomposition, relevant the nanometer rare earth red phosphors were obtained. The thermal changes, structure, size, morphology and luminescent properties of phosphors are investigated by means of TG-DSC , XRD, SEM, TEM. We have obtained high performance nano-sized Y₂O₃: Eu³⁺ red phosphors. About effecting factor and reason of surfactant on the size and morphology of powder are studied. some creative results are acquired.We have get a simple and direct, easy operation, good effect method for preparing nano-sized rare earth phosphors by means of mechanical solid state chemical reaction. The mixed precursors of Y and Eu have prepared by using H₂C₂O₄ · 2H₂O as ligand. The "ball milling method" is better compare with "hand milling mothod" .According to mechanism of thermal decomposition, we have acquired nanometer Y₂O₃: Eu³⁺ powder. by using data of thermal analysis (TG-DSC) and controlling appropriate temperature parameter, The testing results show that the Y₂O₃: Eu³⁺ have cubic system structure, the cell parameter (a) have increased, the average size of the particles is within 30⁵0nm, and the morphology of Y₂O₃: Eu³⁺ is sphericity.By Studying on the luminescent properties of Y₂O₃: Eu³⁺ , the results indicate that nanoscale Y₂O₃: Eu³⁺ phosphors has a high intensity and broad emission band, and the maxium excitation spectra peaks is atλ_ex=249nm, red-shift happened, and the maxium emission spectra peaks is at λ_em=611nm corresponding ⁵D₀→⁷F₂ transition, blue-shift 7nm.The effects of luminescence intensity of Y₂O₃: Eu³⁺ phosphors by Eu concentration and temperature are studied, and the optimal concentration and temperature have been found. It demonstrates that the luminescence intensity of Y₂O₃: Eu³⁺ phosphors have increased with Eu concentration, the optimal Eu concentration is 10%. It is also found the Eu³⁺ critical concentration of Y₂O₃: Eu³⁺ powders is increased obviously than micron crystal (6%), and the particle size and crystallization degree of Y₂O₃: Eu³⁺ increases with the increasing temperature. The luminescence intensity of Y₂O₃: Eu³⁺ is increased slowlywith annealing temperature up to 1100°C, and the powders obtain exhibits a normal size distribution, and the particle size is about 1-2 u m.The study on affecting precursors and finally production by surfactant have been carried out in the present thesis. The results show that surfactant can improve dispersing and decrease particle size of production.Through the present study of using the mechanical solid state chemical reaction to synthesize nano-sized rare earth phosphors, the use areas of mechanical solid state chemical reaction can be broadened and the method or measure about the study of nano-sized rare earth phosphors has been developed.