Improvement of critical current density of RE Ba ₂ Cu ₃ O _7-δ by increase in configurational entropy of mixing

Abstract

RE Ba 2 Cu 3 O 7- δ ( RE 123, RE : rare earth) is one of the high-temperature superconductors with a transition temperature ( T c ) exceeding 90 K. Because of its high- T c and large critical current density ( J c ) under magnetic fields, RE 123 superconductors have been expected to play a key role in superconductivity application. To accelerate application researches on RE 123-based devices, further improvements of J c characteristics have been desired. In this study, we investigated the effects of high-entropy alloying at the RE site on the superconducting properties, through the measurements of local (intra-grain) J c ( J c local ) by a remanent magnetization method. We found that J c local shows a trend to be improved when four or five RE elements are mixed at the RE site, which results in high configurational entropy of mixing (Δ S mix ). All samples exhibited an order of few MA cm −2 which is a criterion for practical application and the highest J c local resulted in a value of around 7.0 MA cm −2 at T = 2.0 K. Because high-entropy alloying can improve J c local of RE 123 superconductors, our entropy-engineering strategy introduced here would be useful for the development of RE 123 superconducting materials available under high magnetic fields.

Analytical electron microscopy study of the composition of BaHfO3 nanoparticles in REBCO films: the influence of rare-earth ionic radii and REBCO composition

“…Recent works on high-entropy oxides 28 showed the successful fabrication of mixed-REE REBCO compounds with more than three REEs. 29–33…”

Growth of REBa2Cu3O x single-crystal whiskers utilizing the concept of high-entropy alloys

“…11,[17][18][19] Furthermore, the superconducting critical current can be increased by introducing the concept of HEAs at the RE site. 20) Although magnets made with RE-123 superconductors can be used for plasma containment in a nuclear fusion reactor, 21) their exposure to the high-energy neutron irradiation environment in these reactors damages them. As previously mentioned, the concept of HEA can be utilized to achieve enhanced irradiation resistance.…”