Improved Bi-2212/Ag performance as a competitor to Bi-2223/Ag in high-Tc superconductor wire applications

The performance of Bi-2212 monofilament tape, produced by the powder-in-tube technique and a decomposition - recovery melt process, was significantly improved by employing an optimum dual atmosphere heat treatment. The atmosphere consists of nitrogen and oxygen applied alternatively at various stages during the process and results in oxygen vacancies within the well aligned crystallites. The investigation was carried out on short (50mm) samples, having a cross-section area of the ceramic core in the range 2x 104 μm2 - 5x104 μm2. An increase in the transport critical current Ic of up to 11A at 77K and up to 68A at 4.2K in zero field (1μV/cm electric field criterion) has been achieved, yielding a current caring capacity Jc in the range (2-4)x 104 A/cm2 at 77K and (1-3)x 105A/cm2 at 4.2K. The pinning energy is weaker than in the Bi-2223 tapes, but almost identical to the Bi-2212 epitaxial films. This, combined with a open-quotes one deformation - one heat treatment (∼30 h)close quotes procedure, makes 2212 a strong competitor for low temperature wire applications