The recent discovery of superconductivity in the iron based superconductorswith very high upper critical fields presents a new possibility for practicalapplications, but fabricating fine-wire is a challenge because of mechanicallyhard and brittle powders and the toxicity and volatility of arsenic. In thispaper, we report the synthesis and the physical characterization of ironpnictide wires and bulks prepared by the powder-in-tube method (PIT). A newclass of high-Tc iron pnictide composite wires, such as LaFeAsO1-xFx,SmFeAsO1-xFx and Sr1-xKxFeAs, has been fabricated by the in situ PIT techniqueusing Fe, Ta and Nb tubes. Microscopy and x-ray analysis show that thesuperconducting core is continuous, and retains phase composition after wiredrawing and heat treatment. Furthermore, the wires exhibit a very weak Jc-fielddependence behavior even at high temperatures. The upper critical field Hc2(0)value can exceed 100 T, surpassing those of MgB2 and all the low temperaturesuperconductors and indicating a strong potential for applications requiringvery high field. These results demonstrate the feasibility of producingsuperconducting pnictide composite wire. We also applied the one step PITmethod to synthesize the iron-based bulks, due to its convenience and safety.In fact, by using this technique, we have successfully discoveredsuperconductivity at 35 K and 15 K in Eu0.7Na0.3Fe2As2 and SmCoFeAsO compounds,respectively. These clearly suggest that the one-step PIT technique is uniqueand versatile and hence can be tailored easily for other rare earth derivativesof novel iron-based superconductors.
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