• O P Arora

      Articles written in Bulletin of Materials Science

    • Synthesis and property evaluation of Y-Ba-Cu-O superconductors

      A Srinivasa Rao O P Arora A Purohit

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      Fine powders of yttrium, barium and copper oxide were synthesized by two different chemical precipitation methods using a spray atomizer. The average particle size in the sintered ceramic was in the range 1–2.5 microns and the superconducting transition temperature of different powders was in the range 60–90 K. With few exceptions, it was found that recalcination and annealing in oxygen will not improve the superconducting transition temperature.

    • Effect of additives on the morphology and superconductivity of YBa2Cu3O6+x ceramic materials

      A Srinivasa Rao L Aprigliano O P Arora

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      The effect of the addition of 0–15 wt.% alumina powder on the grain size, morphology and superconducting properties of sintered YBa2Cu3O6+x was investigated as a function of alumina concentration in the composites. The results suggest that the grain size of YBa2Cu3O6+x decreases with an increase in the additive concentration. Some surface erosion of the YBa2Cu3O6+x grains was also noticeable in Al2O3/YBa2Cu3O6+x composites. The results also indicate that the additive tends to stabilize the nonsuperconducting tetragonal phase of the YBa2Cu3O6+x at the expense of the superconducting orthorhombic crystal phase.

    • Some new results in porous silicon

      V K Jain Amita Gupta C R Jalwania Adarsh Kumar G K Singhal O P Arora D S Ahuja P P Puri R Singh M Pal

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      Efforts have been made to see the effect of some standard microelectronic processing steps on porous silicon. Our diffusion experiments for making p-n junctions confirm that this material can withstand high temperatures of the order of 800°C to 1000°C. A new technique for photolithography has been suggested to obtain porous silicon in selected areas. Etch stop method to control the thickness of the porous layer and an organic protective layer for porous silicon have also been suggested. Models proposed by other workers to explain luminescence in porous silicon are not sufficient to explain many experimental observations. A hybrid model is suggested.

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