• Manoj M Hardias

      Articles written in Bulletin of Materials Science

    • Microstructure evolution in chelated partially hydrolysed alumina sols during sonogelling

      Manoj M Hardias Jayesh R Bellare

      More Details Abstract Fulltext PDF

      Optically transparent alumina sonogels with optical transmittance of over 90% have been prepared by chemically modifying a partially hydrolysed aluminium sec-butoxide precursor with ethyl acetoacetate. Chelating the alkoxide in a 1:2 molar ratio has permitted an enhanced control over microstructural changes during the sol to sonogel synthesis. Particle size and morphology changes during controlled sonogelling indicate that the sol to sonogel evolution in chelated alkoxides occurs by a dissolution-nucleation process in which the chelated species dissolves and aluminium hydroxide nucleates. The chelated agglomerates break down with increasing amount of water, and finally dissolve into the alcohol rich medium. The breakdown of chelated agglomerates is accompanied by the formation of nanosized aluminium hydroxide particles which grow with water addition into aggregated micron sized, spherical species. The chelated agglomerates evolve from a spherical geometry to a cylindrical morphology to a tapelike structure with a preferred orientation, and finally to a wavy sheet-like matrix. The nano-aluminium hydroxide particles increase in size at every water addition and grow to about 1 μm at the sonogel point.

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      Posted on October 12, 2020

      Prof. Subi Jacob George — Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur, Bengaluru
      Chemical Sciences 2020

      Prof. Surajit Dhara — School of Physics, University of Hyderabad, Hyderabad
      Physical Sciences 2020

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      Posted on July 25, 2019

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