Superior transport current densities in (Ba, K)Fe2As2 superconducting tapes realized by combined strengthening of grain texture and flux pinning

• Published in: Journal of alloys and compounds 2024-09, Vol.1000, Article 175081
• Main Authors: Yang, Peng, Wang, Dongliang, Yao, Chao, Guo, Wenwen, Huang, He, Han, Meng, Tu, Chang, Liu, Fang, Jiang, Donghui, Ma, Yanwei
• Format: Article
• Language: English
• Subjects: Critical current density; Flux pinning; Hot isostatic pressing; Iron-based superconductors; Superconducting tapes
• ISSN: 0925-8388; 1873-4669
• DOI: 10.1016/j.jallcom.2024.175081

Iron-based superconductors, characterized by a high upper critical field and small anisotropy, have been regarded as prospective candidate material for high magnetic field applications. For such applications, it is essential to develop iron-based superconducting wires and tapes with high in-field critical current density (Jc). In view of material microstructure, large-sized superconducting grains with high-degree of grain texture are preferable for high efficiency current transportation, but on the other hand will sacrifice some grain boundaries that act as potential flux pinning centers. Here, based on powder-in-tube method, a novel approach combining medium temperature pressing and hot isostatic pressing was developed for the fabrication of Cu/Ag composite sheathed (Ba, K)Fe2As2 (Ba-122) iron-based superconducting tapes. Microstructural analysis reveals lager grain size and improved grain texture produced by the combined processes, and at the same time, high-density nano-size dislocations were induced in grains, which further enhanced the current carrying ability at high field region. As a result, high transport Jc of 1.6×105 A/cm2 at 4.2 K and 10 T was obtained for the Ba-122 tapes, and more importantly, due to the significantly reduced field dependence of Jc, the transport Jc was still kept above the practical level of 105 A/cm2 at high fields up to 25 T. At 25 T, the value of Jc exceeds 60 % of its value at 10 T, indicating a minimal reduction in iron-based superconducting wires and tapes. This study demonstrates a favorable microstructure that will help to approach superior current transport performance under high magnetic fields for iron-based superconductors. •A novel heat treatment method that combines medium-temperature pressing and hot isostatic pressing is proposed.•The large-size superconducting grains and the high degree of texture are preferable for current transportation.•The increase of defect concentration inside the superconducting core can effectively strengthen the flux pinning.•The transport Jc of the Cu/Ag sheathed iron-based superconductors tapes exceeds 105 A /cm2 at 4.2K and 25 T.