Synthesis of c-axis textured CaKFe4As4 superconducting bulk via spark plasma texturing technique

Abstract

Grain alignment is a key factor that determines the performance of a superconducting bulk. In this study, the spark plasma texturing (SPT) technique was used to fabricate a CaKFe4As4 superconducting bulk. X-ray diffraction and electron backscatter diffraction revealed that the c-axes of the CaKFe4As4 grains in the SPT bulk are aligned, demonstrating that the SPT technique is effective in achieving c-axis texture. In addition, chemical composition analysis showed that oxide impurities, which affect the grain boundary characteristics that determine the inter-grain critical current density (Jc), are randomly distributed in the SPT bulk. Magnetization measurements showed high Jc values of the SPT bulk, reaching 127 kA cm−2 and 26 kA cm−2 at 4.2 K under a self-field and magnetic field of 5 T, respectively. These results suggest that the SPT technique is a promising approach for obtaining a high-performance superconducting bulk material for high-field applications.