Mechanical and Superconducting Properties of Ag/YBCO Composite Superconductors Reinforced by the Addition of Zr

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Abstract
The composite high TC superconductor Ag/YBCO reinforced by adding Zr has been synthesized by sintering a compressed mixture of ZrxYBa2Cu3O7-δ(0≤x≤1.0) and Ag powders at various ratios. The flexural strength in the Ag/ZYBCO reached its maximum value of 280 MPa at the composition x=0.8 and 33 vol.%Ag, being more than 5 times as large as that in the sintered YBCO. In addition, the presence of Ag can endow the plasticity while maintaining the superconducting transition temperature above about 80 K. Both the flexural strength and the Vickers hardness are enhanced in magnitude comparable to those for commercial alumina and magnesia. The enhanced mechanical strength is attributed to the unique microstructure, in which dispersed Ag particles remain intact with the Zr-bearing YBCO matrix, whereas CuO and BaZrO3 precipitates in the 123-phase matrix act to reinforce the ceramic without disrupting the superconducting channel.