科研之友
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摘要
The effects of Ag dopants on the superconducting properties of YBCO bulk samples, prepared under solid-state reaction method, have been studied by resistivity-temperature (rho-T), X-ray diffraction (XRD), scanning electron microscope (SEM), bulk density, AC susceptibility, DC magnetization measurements, and theoretical analysis. Small Ag substitutions (xa parts per thousand currency sign0.10) do not effect T (c) of pure YBa2Cu3-x Ag (x) O7-delta , while we observed small decreases of 1.5 K for larger doping levels (xa parts per thousand yen0.15). AC susceptibility measurements for sintered YBCO pellets have been performed as a function of temperatures at constant frequency and AC field amplitude in the absence of DC bias field. The critical current densities (J (c) ) have been estimated as a function of magnetic field from the magnetization data employing Bean%26apos;s critical state model. The increase in Ag amount (x) in YBa2Cu3-x Ag (x) O7-delta (xa parts per thousand yen0.10) system effectively decreases the intragrain critical current density, which is attributed to the reduced connectivity between the grain boundaries. In the case of small additions (x=0.05), Ag atoms fill partly the pores, leading better crystallization of the grains.
- 出版日期2012-7
