High-field magnetisation and the critical current density in superconducting BiSrCaCu<sub>2</sub>O<sub>x</sub>
P A J de Groot; P C Lanchester; M T Weller; J R Grasmeder; G P Rapson; C E Meats; P A J de Groot; Dept. of Phys., Southampton Univ., UK; P C Lanchester; Dept. of Phys., Southampton Univ., UK; M T Weller; Dept. of Phys., Southampton Univ., UK; J R Grasmeder; Dept. of Phys., Southampton Univ., UK; G P Rapson; Dept. of Phys., Southampton Univ., UK; C E Meats; Dept. of Phys., Southampton Univ., UK
Журнал:
Journal of Physics F: Metal Physics
Дата:
1988-06-01
Аннотация:
Samples of notional composition BiSrCaCu<sub>2</sub>O<sub>x</sub> have been prepared and shown to have a majority phase with lattice parameters a=5.395(3) AA, b=5.406(5) AA and c=30.84(1) AA which is superconducting below 80 K. Both the low-field DC magnetisation and resistivity indicate the presence of a minority superconducting phase with T<sub>c</sub>>100 K. The intragrain critical current density J<sub>c</sub> inferred from high-field magnetisation measurements on powder samples is estimated to be 5*10<sup>5</sup> A cm<sup>-2</sup> at 4.2 K and 1 T, which is similar to that observed in YBa<sub>2</sub>Cu<sub>3</sub>O<sub>7</sub>. The form of the temperature and field dependence of J<sub>c</sub> is also similar to that observed in YBa<sub>2</sub>Cu<sub>3</sub>O<sub>7</sub>. However, relaxation effects in the magnetisation are more pronounced, which is indicative of smaller flux pinning especially at high temperatures.
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