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Keywords:

  • 74.25.Fy;
  • 74.25.Ha;
  • 74.25.Sv;
  • 74.72.Hs;
  • 84.81.Bd;
  • 81.40.Rs

Abstract

In this work we present the influence of annealing conditions on superconducting properties of (Bi,Pb)-Sr-Ca-Cu-O high temperature superconductors prepared by the glass-ceramic method. Superconducting (Bi,Pb)-Sr-Ca-Cu-O samples were obtained by annealing of amorphous (Bi0.8Pb0.2)4Sr3Ca3Cu4Ox at temperatures between 750 °C and 865 °C for various time intervals between 1 minute and 43 hours. The electrical and superconducting properties of the material change during annealing because oxide superconductors belonging to the bismuth family (Bi,Pb)2Sr2CuOx (2201), (Bi,Pb)2Sr2CaCu2Ox (2212) and (Bi,Pb)2Sr2Ca2Cu3Ox (2223) crystallise forming a granular metal and superconductor. Low temperature resistivity and magnetic measurements show that during the growth of crystalline phases superconducting properties develop rapidly. Measurements of magnetisation reveal that isolated grains of superconducting 2212 phase crystallise already in the first minute of annealing at 850 °C. Further development of superconducting phases leads to subsequent improvement of superconducting properties. Properties of the material (e.g. critical temperature, critical current) and kinetics of changes depend on the temperature and time of annealing. The highest critical current densities were obtained for samples annealed at 850 °C for 43 hours. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)