• A J Singh

      Articles written in Bulletin of Materials Science

    • Synthesis and single crystal growth of gallium phosphide by the liquid encapsulated vertical Bridgman technique

      K Govinda Rajan N V Chandra Shekar G V N Rao A J Singh R M Iyer

      More Details Abstract Fulltext PDF

      Gallium phosphide is a typical III–V compound semiconductor and is also an important electronic material. The synthesis and single crystal growth of this compound by melt methods is rendered very difficult because of the large phosphorus vapour pressure. A high pressure vessel with internal heating and a quartz reactor was first developed for the direct synthesis of gallium phosphide. The crystal growth was carried out in a second high pressure chamber rated for 100 bars gas pressure and equipped with the paraphernalia for crystal growth. Single crystals of gallium phosphide were grown from the polycrystalline starting material by the vertical Bridgman method and the vapour pressure problem was overcome by encapsulating the melt in a column of molten boric oxide. Both boron nitride and silica were employed as crucibles, and with the former, single crystal rods of 8–10 mm diameter and 10–15 mm length were obtained.

    • A laboratory design for uniaxial hot pressing

      D S Mungekar K B Bhatt A J Singh

      More Details Abstract Fulltext PDF

      A design to hot press uniaxially compacts of 12 mm diameter and 15 mm long and its assembly has been described. The hot press was successfully employed to demonstrate conversion of BN powder into hexagonal machinable variety at 1800°C and 80 bars pressure.

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    • Dr Shanti Swarup Bhatnagar for Science and Technology

      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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