Fabrication Of Bulk Superconductors Research Articles

Superconducting properties and mechanical strength of MgO fibres reinforced bulk Bi-2212 superconductor ceramics

Fabrication of bulk superconductors with optimum superconducting properties and stable mechanical behaviour is essential for the application of high-temperature superconducting ceramics in power engineering. In such application, high critical current density Jc and excellent mechanical stability are among the most important properties. In this study, 3–8 wt-%MgO fibres are added to Bi-2212 superconductor powder. The MgO fibres are prepared in-house using the sol–gel route. The Bi-2212/MgO fibres compounds are heat treated, followed by partial-melting and slow-cooling. The mechanical strength of the samples is studied by conducting the compression test. From the results, the addition of 5%MgO fibres is found to improve the texture of the Bi-2212/MgO fibres ceramics without degrading the transition temperature Tc if compared with the other samples. In addition, the Jc values are enhanced due to the addition of the MgO fibres that significantly improved the texture of the compounds and the grain connectivity within the grains. Significantly higher stiffness, strength and toughness are observed in MgO added samples at room temperature.

Fabrication of bulk superconductors YBa2Cu3?xTexO7?? with highly oriented layer structure using the melt-texture growth process

We report on the successful fabrication of bulk samples satisfying the nominal composition YBa2Cu3−xTexO7−δ and containing highly single-crystal-like texture. While this type of crystal growing process is not new, our process requires only the existence of spatial temperature gradient in some parts of the common tube furnace. The samples with tellurium were found to be much more stable and better superconductors than the Y-123 specimen. Large layer textures with cross-section ∼50×500μm2 were observed to grow inside the usual bulk sample. The critical currents were measured by the d.c. magnetization method and found to be easily greater than 6000 A cm−2 for the samples with Te.