Effect of sheath materials on the microstructure and superconducting properties of SmO0.7F0.3FeAs wires

Fe/Ti, Nb, and Ta sheathed SmO0.7F0.3FeAs wires were manufactured using the powder-in-tube method. A comparative study was made of the effect of sheath material on the microstructure and superconducting properties of the SmO0.7F0.3FeAs wires. Among these sheath materials, the penetration depth of Ta into the superconducting core is the largest. There was nearly no difference in the critical transition temperature of the SmO0.7F0.3FeAs wires sheathed with different materials, and the upper critical fields were approximately the same. On the other hand, it was found that Nb-sheathed wires had a higher superconducting current density than the others. Impurities existing in the superconducting core were thought to be one of the most important factors that affected the critical current density of the SmO0.7F0.3FeAs wires.