Effects of high-pressure annealing on critical current density in 1 2 2 type iron pnictide wires

• (AE, K)Fe2As2 (AE: Ba, Sr) superconducting wires were prepared under high pressure.
• The transport Jcs have reached 37 and 48 kA/cm2 under self-field.
• Large intergranular Jc in the wire cores were confirmed by magneto optical imaging.
• Couplings between superconducting grains were improved by high pressure annealing.

We have fabricated (Ba,K)Fe2As2 and (Sr,K)Fe2As2 superconducting wires through an powder-in-tube (PIT) method using hot isostatic pressing (HIP) technique. The transport critical current densities (Jc) have reached 37 kA/cm2 and 48 kA/cm2 under self-field, and 3.0 kA/cm2 and 1.8 kA/cm2 under magnetic field of 90 kOe, at 4.2 K in the (Ba,K)Fe2As2 and (Sr,K)Fe2As2 wire, respectively. Magneto-optical (MO) imaging of the wires confirmed the large intergranular Jc in the wire core due to the improvement of couplings between superconducting grains by high-pressure annealing.