Yuichi Nakamura1, Kaori Tachibana1,Takashi Yoshida2 and Hiroyuki Fujimoto1
1Railway Technical Research Institute, Kokubunji 185-8540
Silver addition to REBa2Cu3Ox(RE123 : RE=Y, Sm, Nd,...) is thought to be effective to improve mechanical properties. However, such improvements were mainly reported in the case of sintered samples and few quantitative studies of the mechanical and superconducting properties on the melt grown samples with silver were reported. In this study, flexural strength and superconducting properties of melt grown Y123 sample with silver were measured to evaluate the effect of silver addition on the mechanical and superconducting properties. The average flexural strength increased as increasing the silver content. However, the minimum strength of the samples was almost the same irrespective of silver content. This means that the silver addition will decrease the defects in the melt grown samples to increase the average strength, but a few defects still remain and keep the minimum strength low. On the other hand, the relation between Jc and the magnetic field of the Y123 sample with silver addition showed a typical peak effect at 77 K.
Furthermore, Tc values of the sample with silver was about 0.8 K higher than that without silver. A reason for this difference of superconducting properties could be explained by the substitution of Ag with Cu in Y123 crystal. Since the substitution will cause the difference in a stable oxygen configuration in Y123, the suitable oxygen annealing condition will differ from with and without silver samples. This will cause the difference in Tc value under the same annealing condition.
(Received April 26, 1999)
superconductive oxide, YBa2Cu3Ox, silver addition, melt process, mechanical property, three point bending test, critical current density, critical temperature, peak effect
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