Realization of practical level current densities in Sr_0.6K_0.4Fe₂As₂ tape conductors for high-field applications

Abstract

122 type pnictide superconductors are of particular interest for high-field applications because of their large upper critical fields H c2 (> 100 T) and low anisotropy γ (<2). Successful magnet applications require fabrication of polycrystalline superconducting wires that exhibit large critical current density J c , which is limited by poor grain coupling and weak-link behavior at grain boundaries.Here we report our recent achievement in the developing Sr 0.6 K 0.4 Fe 2 As 2 tapes with transport J c up to 0.1 MA/cm 2 at 10 T and 4.2 K. This value is by far the highest ever recorded for iron based superconducting wires and has surpassed the threshold for practical application. The synergy effects of enhanced grain connectivity, alleviation of the weak-link behavior at grain boundaries, and the strong intrinsic pinning characteristics led to the superior J c performance exhibited in our samples. This advanced J c result opens up the possibility for iron-pnictide superconducting wires to win the race in high-field magnet applications.

Critical current density and microstructure of iron sheathed multifilamentary Sr1−xKxFe2As2/Ag composite conductors

“…Recently, by hot and cold uniaxial pressing process to achieve highly densified superconducting phase, the transport J c in silver sheathed mono-and 7-filament Sr-122 and Ba-122 tapes has been greatly improved [14,15]. At present, the highest J c value, which was achieved in hot pressed monofilamentary tapes, has reached 1.2×10 5 A cm -2 at 4.2 K and 10 T [16].…”

Crystal structure instability of FeSe grains: Formation of non-superconducting phase at the grain surface

“…Owing to their high superconductivity performance at high magnetic fields, one of the potential applications of Fe-based superconductors is a superconducting wire or tape for magnets. Thus far, several types of Fe-based superconducting wires have been fabricated using A1-xKxFe2As2 (A = Ba, and Sr) [5][6][7][8], SmFeAsO1-xFx [9][10][11], and Fe chalcogenides (FeSe-based [12][13][14][15][16][17][18][19] or FeTe-based [20][21][22][23][24] superconductors). The FeAs-based superconducting wires (particularly, Ba1-xKxFe2As2 and Sr1-xKxFe2As2 wires) fabricated by the powder-in-tube (PIT) method showed a high critical current density (Jc).…”

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

“…Mainly, two pressing methods for the fabrication of IBS wires and tapes have been proven to be effective in enhancing J c , namely, uniaxial pressing for the tape [32][33][34][35][36] and hot isostatic pressing (HIP) for round wires [21,23,39,40]. Although uniaxial-press method has realized the highest J c value, it cannot be used for the fabrication of round wires.…”