Development and Characterization of P-doped Ba-122 Superconducting Tapes

Among the recently discovered Fe-based superconducting compounds, the Ba-122 phase has proved to be the more attracting for the development of powder in tube (PIT) processed conductors. In fact, after some years of development, critical current densities (Jc ) of about 105 A/cm2 at 4.2 K and magnetic fields up to 10Thave been obtained in (Ba0.6K0.4 )Fe2As2, PITwires and tapes. To develop a safe upscaling method, the synthesis of the powders is a crucial point. In order to avoid the use of highly reactive K we have developed BaFe2 (P1-xAsx )2 PIT tapes. This compound has proved to be very stable and in form of crystals and thin films exhibits excellent critical current:We succeeded in manufacturing PIT tapes with this phase with Jc values of about 103 A/cm2 at 4.2 K in self-field. Detailed microstructural and chemical investigations of the samples have been performed by high-resolution TEM, scanning TEM, and electron energy loss spectrometry analysis. A deformation network inside the grains that can induce strong pinning has been observed. However, chemical inhomogeneities at the grain boundaries are also present, which limit the transport current.