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      https://www.ias.ac.in/article/fulltext/boms/014/03/0681-0686

    • Keywords

       

      Positron annihilation; Doppler broadening

    • Abstract

       

      Doppler-broadened annihilation radiation spectra have been measured as a function of temperature from 77 K to 300 K, for several high temperature oxide superconductors viz single-phase YBCO, single- and mixed-phase Tl-Ca-Ba-Cu-O and Bi-Ca-Sr-Cu-O compounds. The temperature-dependent parameters extracted respond to a change at the onset of superconducting transition. The observations point to involvement of oxygen valence electrons at the onset of superconducting transition. Also a possible structural change and/or increase in electron density at the oxygen vacancy/defect sites seem to accompany the transition. In addition, the parameters derived are seen to be sensitive to the presence of more than one superconducting phases in mixed phase samples.

    • Author Affiliations

       

      P K Pujari1 T Datta1 Satya Prakash1 S B Manohar1 I K Gopalakrishnan1 G M Phatak1 J V Yakhmi1 PVPSS Sastry1 R M Iyer1

      1. Chemical Group, Bhabha Atomic Research Centre, Bombay - 400 085, India
    • Dates

       
  • Bulletin of Materials Science | News

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