• Study of the impact of HgO addition and low-field magnetic relaxation behaviour in granular high-Tc superconductors

    • Fulltext


        Click here to view fulltext PDF

      Permanent link:

    • Keywords


      Hg addition; oxygen source; magnetic relaxation; grain boundary coupling energy; flux pinning energy

    • Abstract


      A series of high-Tc superconductors have been prepared with the HgO addition/substitution. Significant improvement in theTconset as well asTc0 was observed in all the cases. Substitution of Hg at the Sr site and Ba site in the case of (Bi, Pb)-Sr-Ca-Cu-O and Y-Ba-Cu-O systems, respectively over a range 0·01–0·6 at% helps in constructing an entire spectrum: improvement ofTc0 up to 0·4 at % in the case of Bi-system and up to 0·03 at % in the case of Y123 system and slight drop inTc thereafter. Such improvement is the result of abundant supply of highly reactive nascent oxygen all through the bulk. HgO decomposes and provides oxygen which helps in maintaining proper oxygen stoichiometry throughout the bulk. No Hg or Hg-based impure phases were observed in the X-ray diffraction spectra. Low-field (10–100 Oe) magnetic relaxation studies reveal faster relaxation of the intergranular critical state in the case of silver added samples as the grain boundary coupling energyEJ becomes quite uniform across the entire bulk which leads to smaller flux pinning energy. The distribution of the pinning energy is evaluated from the observed relaxation pattern and is found to be narrower in the case of silver added samples. It was also observed that the transportJc ∼ exp[−ΔTc/Tc0] and the flux pinning energyU ∼ ΔTc, where ΔTc is the transition width and is a measure of the inhomogeneity within the sample. Such relationships may help in devising a strategy for achieving highJc, highU yet low ΔTc. Silver addition turns out to be an effective tool in tailoring the sample properties depending on requirement.

    • Author Affiliations


      R G Sharma1 S Lahiry1 A Pandey1 Dipten Bhattacharya1

      1. National Physical Laboratory, New Delhi - 110 012, India
    • Dates

  • Bulletin of Materials Science | News

    • 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

    • Editorial Note on Continuous Article Publication

      Posted on July 25, 2019

      Click here for Editorial Note on CAP Mode

© 2017-2019 Indian Academy of Sciences, Bengaluru.