X-ray diffraction characterization of thermally annealed nanometric alumina powder

G. Kimmel, D. Dayan, J. Zabicky

    Research output: Contribution to journalConference articlepeer-review

    Abstract

    Nanometric powders prepared by a modification of the sol-gel method served as precursors of transition aluminas and ultimately of corundum. This work focused on line broadening effects accompanying the thermal annealing of these powders, that was carried out at temperatures ranging from 800 to 1600 °C, for 1 to 24 hours. Below 1150 °C only transition aluminas were obtained. At 1150 °C corundum was gradually formed from a mixture of γ and θ phases. At 1200 °C corundum formation was complete after one hour. The fast Williamson-Hall method using the entire diffraction spectrum was adopted for line broadening analysis, providing an effective tool for resolving strain-size effects. Crystallite size was shown to depend mainly on temperature, with a slight influence of annealing time. SEM observation of selected samples supported this contention. The relaxation of internal strain was investigated as a function of annealing time. The highest strain levels and lowest relaxation rates were found in the low temperature range. At high temperatures the measured strain was minimal. This led to the conclusion that the observed strain stemmed mainly from the growth process of nanometric alumina powders, while thermal stress was negligible.

    Original languageEnglish
    Pages (from-to)II/-
    JournalMaterials Science Forum
    Volume321
    StatePublished - 1 Jan 2000
    EventProceedings of the 1998 6th European Powder Diffraction Conference (EPDIC 6) - Budapest, Hung
    Duration: 22 Aug 199825 Aug 1998

    ASJC Scopus subject areas

    • Materials Science (all)
    • Condensed Matter Physics
    • Mechanics of Materials
    • Mechanical Engineering

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