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      https://www.ias.ac.in/article/fulltext/boms/034/04/0859-0864

    • Keywords

       

      MgAl2O4 spinel; Al2O3; solid solution; phase transformation; X-ray diffraction.

    • Abstract

       

      Although existence of MgAl2O4–𝛾-Al2O3 solid solution has been reported in the past, the detailed interactions have not been explored completely. For the first time, we report here a mathematical framework for the detailed solid solution interactions of 𝛾-Al2O3 in MgAl2O4 (spinel). To investigate the solid solubility of 𝛾-Al2O3 in MgAl2O4, Mg–Al spinel (MgO–𝑛Al2O3; 𝑛 = 1, 1.5, 3, 4.5 and an arbitrary high value 30) precursors have been heat treated at 1000°C. Presence of only non-stoichiometric MgAl2O4 phase up to 𝑛 = 4.5 at 1000°C indicates that alumina (as 𝛾-Al2O3) present beyond stoichiometry gets completely accommodated in MgAl2O4 in the form of solid solution. 𝛾 → 𝛼 alumina phase transformation and its subsequent separation from MgAl2O4 has been observed in the Mg–Al spinel powders (𝑛 > 1) when the 1000°C heat treated materials are calcined at 1200°C. In the mathematical framework, unit cell of MgAl2O4 (Mg8Al16O32) has been considered for the solid solution interactions (substitution of Mg2+ ions by Al3+ ions) with 𝛾-Al2O3. It is suggested that combination of unit cells of MgAl2O4 takes part in the interactions when 𝑛 > 5 (MgO–𝑛Al2O3).

    • Author Affiliations

       

      Soumen Pal1 A K Bandyopadhyay1 S Mukherjee2 B N Samaddar3 P G Pal1

      1. Department of Ceramic Technology, Government College of Engineering and Ceramic Technology, Kolkata 700 010, India
      2. School of Materials Science and Nanotechnology, Department of Metallurgical and Material Engineering, Jadavpur University, Kolkata 700 032, India
      3. Ex-emeritus Professor (AICTE), Department of Metallurgical and Material Engineering, Jadavpur University, Kolkata 700 032, India
    • Dates

       
  • Bulletin of Materials Science | News

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