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  • 1
    Electronic Resource
    Electronic Resource
    Westerville, Ohio : American Ceramics Society
    Journal of the American Ceramic Society 85 (2002), S. 0 
    ISSN: 1551-2916
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Cerium oxides are used as surrogates for plutonium oxides because of the similarities in their thermodynamic properties. In this study, the stability limits of both CeGaO3 and PuGaO3 with respect to the partial pressure of oxygen and temperature have been predicted by theoretical calculations. Using the results of the calculations as guidance, mixtures of CeO2 and Ga2O3 have been prepared and thermally treated at 1273, 1473, and 1673 K, in atmosphere of air, argon, or Ar–6% H2. In the samples annealed under low oxygen partial pressures, the CeGaO3 perovskite-type compound was identified. Based on Rietveld structure refinement, the orthorhombic space group (Pnma, 62) was confirmed.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
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  • 2
    Electronic Resource
    Electronic Resource
    Westerville, Ohio : American Ceramics Society
    Journal of the American Ceramic Society 82 (1999), S. 0 
    ISSN: 1551-2916
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The oxidation process of MoSi2 is very complex, and controversial results have been reported, especially for the early-stage oxidation before the formation of passive SiO2 film. Most oxidation studies have been carried out on bulk consolidated samples, and the early stage of oxidation has not been studied. In this investigation, very fine MoSi2 powder with an average particle size of 1.6 μm was used. Such a fine particle size makes it easier to study the early stages of oxidation since a significant portion of the powder is oxidized before the formation of passive SiO2 film. The oxidation kinetics of commercial MoSi2-SiC and MoSi2-Si3N4 powder mixtures were also studied for comparison. Weight changes were measured at discrete time intervals at 500° to 1100°C in 0.14 atm of oxygen. X-ray diffraction was used to identify the phases formed during oxidation. Our results show the formation of MoO3 phase and an associated weight gain at low temperatures (500° and 600°C). At temperatures higher than 900°C, Mo5Si3 phase formed first and was subsequently oxidized to solid SiO2 and volatile MoO3, resulting in an initial weight gain followed by subsequent weight loss. A model based on the assumption that oxidation kinetics of both MoSi2 and Mo5Si3 are proportional to their fractions in the system describes the experimental data well.
    Type of Medium: Electronic Resource
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