Defects, Diffusion and Dopants in Sillimanite

Raveena Sukumar, Poobalasuntharam Iyngaran, Navaratnarajah Kuganathan, Alexander Chroneos

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    Abstract

    Aluminum silicate based mineral “Sillimanite” (Al2SiO5) is important in the industrial preparation of aluminum-silicon alloys and cement. In the present study classical pair potential simulations are used to examine the intrinsic defect processes, diffusion pathways of Al3+ and O2- ions together with their activation energies and promising dopants on the Al and Si sites in Al2SiO5. The cation anti-site (Al-Si) defect cluster is calculated to be the most favorable defect, highlighting the cation disorder in this material, in agreement with the experiment. The cation disorder is important as this defect can change the mechanical and chemical properties of Al2SiO5. The Al3+ ions and O2-
    ions migrate in the c direction with corresponding activation energies of 2.26 eV and 2.75 eV inferring slow ion diffusion. The prominent isovalent dopants on the Al and Si sites are found to be the Ga and Ge, respectively, suggesting that they can be used to prevent phase transformation and tune the
    properties of sillimanite.
    Original languageEnglish
    Article number857
    Pages (from-to)1-10
    Number of pages10
    JournalMinerals
    Volume10
    Issue number10
    DOIs
    Publication statusPublished - 29 Sep 2020

    Bibliographical note

    This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

    Funder

    European Union’s H2020 Program under Grant Agreement no. 824072–HARVESTORE

    Keywords

    • Defects
    • Diffusion
    • Dopants
    • Sillimanite
    • Solution energy

    ASJC Scopus subject areas

    • Geotechnical Engineering and Engineering Geology
    • Geology

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