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 10 T have been obtained in (Ba0.6K0.4)Fe2As2, PIT wires 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.
Development and Characterization of P-doped Ba-122 Superconducting Tapes
PUTTI, MARINA
2017-01-01
Abstract
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 10 T have been obtained in (Ba0.6K0.4)Fe2As2, PIT wires 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.
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