Microstructure and transport critical current in Sr_0.6K _0.4Fe₂As₂ superconducting tapes prepared by cold pressing

Fe-clad Sr0.6K0.4Fe2As2 (Sr-122) superconducting tapes were fabricated by cold uniaxial pressing. It is found that the pressing can improve the mass density and induce c-axis texture in the Sr-122 core. With an increase of pressure from 0.6 to 1.8 GPa, the degree of texture increases monotonically. The transport current density (Jc) is correspondingly improved until the applied pressure comes up to 1.4 GPa, and finally becomes saturated at 1.8 GPa. A transport Jc as high as 16.8 kA cm^-2 (at 4.2 K in self-field) is achieved at 1.4 GPa. The saturation effect of transport Jc can be ascribed to the microcracks in the grains induced by the strong deformation force when the applied pressure is high.