Alignment of YBa2Cu3O7-x and Ag─YBa2Cu3O7-x Composites at ∼930°C by Eutectic Formation |
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Authors: | Ji-Ping Zhou Charles C Sorrell Shi-Xue Dou Miles H Apperley |
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Affiliation: | School of Materials Science and Engineering, University of New South Wales, Kensington, New South Wales 2033, Australia |
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Abstract: | The present work describes a new technique to synthesize aligned YBa2Cu3O7- x and Ag─YBa2Cu3O7- x superconducting composites from Ba- and Cu-deficient compositions (relative to YBa2Cu3O7- x ) plus BaCuO2. For YBa2Cu3O7- x , high transition temperature midpoint Tc (91 K), temperature of zero resistivity T 0 (90 K), and critical current density Jc (>3000 A°Cm−2 at 77 K) were achieved by using this technique. This procedure provides the potential for using a reliable and reproducible densification and alignment technique alternative to partial or full melting. The composite is highly aligned, with an average grain size of ∼1 to 2 mm and domains of width greater than 5 mm. The initial phase assemblage consists of YBa2Cu3O7- x (123) as the major phase plus YBa2CuO5 (211) CuO as minor phases. The BaCuO2 is added to the Ba- and Cu-deficient starting composition in order to assist in the formation of a CuO-rich liquid as well as to compensate for the Ba and Cu deficiences in 123. Since the liquid forms at ∼900°C and is compatible with 123, it can be used to facilitate alignment of 123 at ∼930°C. The addition of Ag to the system results in eutectic formation with the (solidified) liquid, substantial filling of the pores during sintering, and improved alignment. |
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Keywords: | superconductors alignment eutectics composites synthesis |
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