High critical current density and low anisotropy in textured Sr1−xKxFe2As2 tapes for high field applications

Abstract

From the application point of view, large critical current densities Jc (H) for superconducting wires are required, preferably for magnetic fields higher than 5 T. Here we show that strong c-axis textured Sr1−xKxFe2As2 tapes with nearly isotropic transport Jc were fabricated by an ex-situ powder-in-tube (PIT) process. At 4.2 K, the Jc values show extremely weak magnetic field dependence and reach high values of 1.7×104 A/cm2 at 10 T and 1.4×104 A/cm2 at 14 T, respectively, these values are by far the highest ever reported for iron based wires and approach the Jc level desired for practical applications. Transmission electron microscopy investigations revealed that amorphous oxide layers at grain boundaries were significantly reduced by Sn addition which resulted in greatly improved intergranular connectivity. Our results demonstrated the strong potential of using iron based superconductors for high field applications.

Enhancement of critical current densities in (Ba,K)Fe2As2wires and tapes using HIP technique

“…The performance of IBS wires and tapes has been much improved by several methods, such as combination of several times of cold press and hot press [21] or only hot press [16,[22][23][24], only cold press [32,35], addition of metals like Ag, Pb, and Sn [25][26][27][28][29][30][31], or by texturing [27,30,31].…”

High transportJcin magnetic fields up to 28 T of stainless steel/Ag double sheathed Ba122 tapes fabricated by scalable rolling process

“…Among these proposed processes, the powder-in-tube (PIT) method seems the most promising technique for practical applications [19][20][21]. Thus, the Ba(Sr)122 PIT wires have been investigated intensively [22][23][24][25][26][27][28][29][30][31], and high J c exceeding the level of 10 4 A/cm 2 at 4.2 K and 10 T has been reported for short samples prepared by applying uniaxial pressing [32][33][34][35].However, unfortunately, pressing processes are usually applicable only for a short sample and it is difficult to attain such high J c values with good reproducibility. For practical applications, it is desirable if high J c values are attained with good reproducibility by rolling, which is easy to scale up to the long length wire production.…”

Large transport critical currents and magneto-optical imaging of textured Sr1−xKxFe2As2superconducting tapes

“…Data shown in figure 1 is based on transport measurements performed on a HT tape that had experienced a very short high temperature at 1100 these results is ascribed to improved grain connections of LT tapes because of dense structure and reducing the inhomogeneities during the low temperature process [15]. Compared to our earlier studies of ex-situ PIT Sr122 tapes [10], the texture processing of the present samples seemed to increase the number of local links and strong links, leading to better connectivity and thus more intergranular current loops.…”

“…field of 10 T were achieved in Sr122/Fe tapes through a texturing process plus Sn addition, which are both effective ways to improve grain connectivity [15]. It is noted that quantification of transport measurements reported so far is almost performed at 4.2 K for convenience.…”