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The Research on Synthesis of Nanocrystalline Ce1-xNdxO2-x/2 Powders by a Low Temperature Combustion Process

Author: GaoYong
Tutor: WangLingLing
School: Hunan University
Course: Materials Physics and Chemistry
Keywords: Low-temperature Combustion Synthesis Nd3+ Doped Cerium Solid Solution Nanocrystalline Powders
CLC: TB383
Type: Master's thesis
Year: 2005
Downloads: 156
Quote: 2
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Abstract


Due to the high oxide ionic conductivity of the solid electrolyte, which is made from the rare earth doped cerium solid solution powders, the ceria-based materials are extensively studied for their applications in intermediate temperature solid-oxide fuel cells （IT-SOFCs）. In this paper, we prepared the Nd3+ doped CeO2 （NDC） solution nanocrystalline powders in glycine-nitrate process （GNP） and citrate acid-nitrate process （CNP） by a new low-temperature combustion synthesis different from the traditional process. We studied the varied fuels, calcination temperature, stoichiometric of G/N or C/N, adiabatic combustion temperature, ignition temperature, and the component, crystalline structure, crystalline size, morphology, specific surface area, oxygen vacancy, doping content by theory calculation and experiment characterization. In addition, we studied the sintering temperature, crystalline structure, density and surface morphology of the sintered bodies, which influence the solid electrolyte praparations and properties greatedly.In the glycine-nitrate combustion process, we calculationed the influence of glycine to nitrate radio to the adiabatic combustion temperature by the propellant chemistry and combustion thermodynamics theories, also studied the influence of the stoichiometric and the calcination temperature to the properties of powders when doping content x equal to 0.2, we confirmed the suitable stoichiometric G/N=1.2. According to the TG-DSC analysis, the combustion process completed in very shortly time, ignition temperature was 257.5℃. The agglomerates consisting of porous particles are observed, which are typical of powders prepared by the combustion technique. All powders exhibited a fluorite-type crystalline structure. The prepared powders also had littler crystalline size approximately 917nm, had only slight agglomerates. The specific surface area was 3847m2·g-1. The crystalline size increased with the increasing of calcination temperature, and the powders had good crystalline shape and purity. The particle size was approximately 40nm. Raman spectrum results indicated that the Raman peak appeared at 465cm-1 is fluorate structure F2g module. The 580cm-1 weak band contributed to the presence of oxide vacancies, increasing with the increased of calcination temperature, which indicated calcination temperature promote oxide vacancies formed. According to the parameter confirmed before, we prepared different doping consent nanocrystalline powders from x=0 to x=0.6. XRD results indicated that crystalline structure have no changed with the doping content increased, which

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