Progress in wire fabrication of iron-based superconductors

Abstract

Abstract:Iron-based superconductors, with T c values up to 55 K, are of great interest for applications, due to their lower anisotropies and ultrahigh upper critical fields. In the past 4 years, great progress has been made in the fabrication of iron-based superconducting wires and tapes using the powder-in-tube (PIT) processing method, including main three types of 122, 11, and 1111 iron-based parent compounds. In this article, an overview of the current state of development of iron-based superconducting wires and tapes is presented. We focus on the fabrication techniques used for 122 pnictide wires and tapes, with an emphasis on their meeting the critical current requirements for making high-performance conductors, such as a combination of using Ag sheath, addition element and optimized heat treatment to realize high J c , ex situ process employed to reduce non-superconducting phases and to obtain a high relative density, and a texture control to improve grain connectivity. Of particular interest is that so far transport J c values above 10 4 A/cm 2 at 4.2 K and 10 T are obtained in 122 type tapes, suggesting that they are prospective candidates for high-field applications. Finally, a perspective and future development of PIT pnictide wires are also given.*

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

“…Nowadays the powder-in-tube (PIT) method has been proved to be a convenient and scalable way to develop iron-based superconducting wires and tapes, and silver is so far the most suitable sheath material for 122 iron pnictides, since it is chemically stable enough to prevent the generation of nonsuperconducting phase at the interface between sheath and 122 phase [13]. 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].…”

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

“…These results strongly suggest that the conductors based on 122 compounds are more promising for high field magnets operating at 20 K [5], where the niobium-based superconductors cannot play a role owing to their lower T c s, and MgB 2 wire is also difficult to be employed because of a very rapid drop of J c with the applied field.…”

Solid state synthesis and characterization of bulk FeTe0.5Se0.5superconductors

“…The FeTe materials can be prepared either in polycrystalline or in single crystal form by using different methods [28][29][30]. In the application side of FeSe and FeTeSe materials, various forms such as, thin/thick films [31,32] and wires/tapes [33][34][35][36] can be prepared and they have capabilities to meet today's technological needs.…”