Enhanced critical current density in K-doped Ba122 polycrystalline bulk superconductors via fast densification

Shinnosuke Tokuta; Yuta Hasegawa; Yusuke Shimada; Akiyasu Yamamoto

doi:10.1016/j.isci.2022.103992

Enhanced critical current density in K-doped Ba122 polycrystalline bulk superconductors via fast densification

iScience. 2022 Feb 26;25(4):103992. doi: 10.1016/j.isci.2022.103992. eCollection 2022 Apr 15.

Authors

Shinnosuke Tokuta¹, Yuta Hasegawa¹, Yusuke Shimada², Akiyasu Yamamoto¹

Affiliations

¹ Department of Applied Physics, Tokyo University of Agriculture and Technology, 2-24-16 Nakacho, Koganei, Tokyo 184-8588, Japan.
² IMR, Tohoku University, Sendai 980-8577, Japan.

Abstract

Iron-based superconductors are expected to be used in strong magnet applications owing to their excellent superconducting properties. The process of sintering a mechanically alloyed precursor powder is effective in achieving a high upper critical field and critical current density in BaFe₂As₂ (Ba122) polycrystalline bulk materials. However, when this process is applied to K-doped Ba122, which shows the highest critical temperature in the Ba122 family, suppressing the vaporization of potassium is challenging. In this study, spark plasma sintering (SPS) method was applied to K-doped Ba122 to achieve fast densification. In contrast to the conventional synthesis method, which requires several tens of hours, optimally K-doped bulks with near theoretical density were obtained after only 5 min of SPS, and the magnetic critical current density reached 10⁵ A/cm² at 5 K. The demonstrated superconducting properties suggest that this fast densification technique is a useful tool for applying K-doped Ba122 to bulk trapped field magnets.

Keywords: Condensed matter physics; Superconductivity; Transport property of condensed matter.