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.