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      https://www.ias.ac.in/article/fulltext/pram/040/05/0391-0398

    • Keywords

       

      Perturbed angular correlation; quadrupole interaction; Hf-doped YBCO; highTc superconductor

    • Abstract

       

      Time differential perturbed angular correlation measurements of the 133–482 keVγ-γ cascade of181Ta in Hf-doped YBa2Cu3O7−x are presented. The181Hf precurser nuclei are incorporated into the sample by thermal neutron irradiation. Two quadrupole interaction frequencies are observed in the as-irradiated sample:vQ1=161±10 MHz with intensityf1=75%, asymmetry parameterη1=0.32 and damping parameter Λ1=0.42, andvQ2=1108±40 MHz withf2=25%,η2=0.62, and Λ2=0.60. On annealing the sample in air at various temperaturesTa and quenching to room temperature,f1 remained nearly constant forTa<600°C andvQ1 for all annealing temperatures indicating that these are insensitive to oxygen stoichiometry. This frequency is interpreted to be due to181Hf substitutingY sites. BeyondTa=600°C,f1 increased and reached a constant value of 90% forTa=800°C. The value ofvQ2 showed a slight variation between 1086 and 1160 MHz, whilef2 remained nearly constant at 25% forTa<600°C. This component is identified to be due to181Hf substituting Cu 1 sites in the Cu-O chains of YBCO. Above 600°CvQ2 decreased and reached a value of 808 MHz beyond 750°C.

    • Author Affiliations

       

      R Govindaraj1 M Premila1 Padma Gopalan1 K P Gopinathan1

      1. Materials Science Division, Indira Gandhi Centre for Atomic Research, Kalpakkam - 603 102, India
    • Dates

       
  • Pramana – Journal of Physics | News

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