Synthesis, Characterization And Properties Of Nanosized Inorganic Non-metal Materials

Nanoparticles and nanocluster materials are a new class of advanced materials exhibiting unique chemical and physical properties compared to those of their bulk materials. Y2O3:Eu and Gd2O3:Eu are efficient red-emission phosphor. Recent studies show that they have significant promise in the field of luminescent materials. In our present work, a simple sol-gel process, in which ethylen-diamine-tetraacetic acid (EDTA) and polyethylene glycol (PEG) are used as the chelating agent and polymerization agent respectively, has been exploited to synthesize Y2O3:Eu and Gd2O3:Eu nanocrystalline. This EDTA route has several remarkable advantages in comparison with other method. Because of the greater ability of EDTA anions to chelate metal cations, and forming very stable and soluble complexes, all of the starting materials are mixed at the molecular or atoms level in a solution, it is easy to control the composition and a high degree of homogeneity is achievable. In addition, the polymerization reaction of EDTA induced by PEG can greatly inhibit cation segregation and /or fluctuation of chemical constitutents. Moreover, low calcining temperature is anticipated because of the high specific surface area of the ultrafme particles existing in their precursor phase along with a high reactivity during subsequent heat treatments. In our work, the formation process, microstructure and luminescent properties of the synthesized Y2O3:Eu and Gd2O3:Eu nanocrystalline were investigated by TG-DTA, FTIR, XRD, SEM/EDX, Fluorescence spectrophotometer respectively. The results show that pure cubic phase Y2O3:Eu and Gd2O3:Eu nanocrystalline have been produced after the precursor calcinated respectively at 600 and 700 for 2h. The nanoparticles are basically spherical in shape. The mean grain size is below 100 nm. Compared with micro-sized Y2O3: Eu and Gd2O3:Eu phosphors prepared by a conventional method, nanosized Y2O3: Eu and Gd2O3:Eu synthesized by the present work, gives a clear blue shift in the emission spectrum, and a clear red shift in the excitation spectrum. Moreover, the quenching concentration of Eu is raised. On the basement of successful synthesis of two-components oxide, EDTA complexing Sol-Gel method was expanded and applied to effectively synthesis nanosized muti-components oxide, such as La1-xSrx Fe O3, LaFe1-xCuxO3, La1-xSrx CoO3, LaCo1-xCuxO3 Because EDTA can bind with most metallic elements of the periodic table, this technique become aversatile tool in the production and study of new nano materials of multi-component complex oxides. A economic and new process has been studied to synthesis La2O3 nanocrystalline, using NH4HCO3 as precipitant. It has been primary reported that organic dispersant has effect of the size and morphology of La2O3. Moreover, it has been found that La2O3 nanocrystalline is unstable in chemical properties. It can easily absorb water and then change into La(OH)3. Using ZnSO4 and (NH4)2S as the raw materials, nanocrystalline ZnS was prepared by the improved precipitation method with the addition of organic dispertant. The effects of reactive conditions on the products were discussed and the proper conditions are determined. We primarily synthesize a series of Ba1-XSrxTi1-ySnyO3 solid solutions nanopowder by low-temperature/low-pressure hydrothermal method under the condition of 150, 0.5Mpa. Because of the doped ions Sr2+ and Sn4+ entering into the matrix lattice evenly and crystallizing completely, the sintered ceramics of the nano-sized powder have dielectric constant ten times higher and dielectric loss sixty percent lower than those of pure BaTiO3 phase at room temperature. The sinter temperature is lower 150~200 than those of micro-sized powder.