[19a-PB2-1~39] 11 超伝導（ポスター）

▼ [19a-PB2-29] Optimization of CaKFe₄As₄ synthesis conditions and investigations of Sn addition effect on the microstructural and superconducting properties

〇(P)PavanKumarNaik Sugali¹、Ishida Shigeyuki¹、Kawashima Kenji²、Iyo Akira¹、Eisaki Hiroshi¹、Ogino Hiraku¹ (1.Electronics and Photonics Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1 Central 2, Umezono, Tsukuba, Ibaraki, 305-8568, Japan、2.IMRA Materials R&D Co., Ltd., Kariya, Aichi 448-0032, Japan)

キーワード：Superconductor, Critical current density, Microstructure

In this work we studied the optimization of synthesis conditions of CaK-1144 polycrystalline powders via a conventional solid-state reaction method in a stainless-steel tube. In addition, the effect of sintering temperature was investigated across the temperature range of 600 ^oC – 900 ^oC for Sn added samples. Beyond 700 ^oC, the sample was decomposed to CaFe₄As₃, 122 and Fe-As phases indicating 700 ^oC is the optimal condition. The occurrence of superconductivity was not influenced by the sintering temperature and observed to be ~32.5 K. Conglutination of weak links (grain boundaries, GB) of the superconducting 1144 grains by the Sn was homogeneous in the Sn added sample sintered at 700 ^oC as evinced by the microstructural and elemental analysis. Field dependence of J_c value at 4.2 K was improved from 12500 A/cm² in as synthesized 1144 to 15500 A/cm² in Sn added sample sintered at 700 ^oC due to improved GB connectivity and flux pinning induced by the interfacial defect density.