• G C Jain

      Articles written in Bulletin of Materials Science

    • Kinetics of the oxidation of CuFeO2 in Cu-Fe-O system

      G C Jain B K Das R Avtar

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      The oxidation kinetics of CuFeO2 in Cu-Fe-O system have been studied between temperature range 500° C and 900° C in an ambient atmosphere containing constant oxygen partial pressure in the flowing nitrogen. Thermogravimetric analysis (TGA) technique was used as the main tool. The oxidation rate was found to decrease and the activation energy calculated from the oxidation rate constants for various composition increased from 8 to 45 k cal/mole on increasing the Fe2O3 content in the system. The value of exponentn in Avrami’s equation=1 − exp (−ktn) also increased from 1·3 to 2·3. The microstructural changes associated with the oxidation have been studied using optical microscopy and correlated with results obtained from thermogravimetric analysis.

    • Etch pit shapes on {110} surfaces of CaF2 crystals

      G C Jain L C Jain T S Murty

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      {110} surfaces of CaF2 crystals are etched with different concentrations of HCl. It is found that concentrated HCl produces characteristic rectangular pyramidal etch pits and 2 volume percent HCl produces boat shaped etch pits. Such variations in the etch pit shapes on {110} surfaces of CaF2 crystals with different concentrations of HCl have been explained. Concentrated H2SO4 is found to be a suitable chemical polisher for these surfaces, the polishing rate is about 0·1μ/min.

    • On the sintering kinetics of titania doped ceramic lanthanum chromite

      K P Bansal S Kumari B K Das G C Jain

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      The sintering behaviour of lanthanum chromite with the addition of 1 to 3 wt% TiO2 was studied. Densification was examined as a function of sintering temperature and TiO2 concentration. The results showed that pure LaCrO3 could not be densified to >75% of the theoretical density, while the densities exceeding 90% of the theoretical were achieved with 3 wt% titania addition at 1600° C.

      Metallographic study reveals a normal grain growth following the rate equationD2D02=kt. Activation energies both for densification and grain growth have been estimated to be ≈ (80±5) k cal/mole in case of 3 wt% TiO2 addition.

    • Surface distortion features on indented CaF2 cleavages

      G C Jain P N Rawat

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      Surface distortion features around static indents on the cleavages of CaF2 single crystals have been investigated by multiple beam interference technique. At room temperature microcracks around such indents nucleate at the sinking in regions. Fizeau fringe patterns (around indents at 200° C) revealed a transition from a three-fold to a six-fold material flow.

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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
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      Posted on July 25, 2019

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