The excellent superconducting properties ofin situpowder-in-tube processed MgB2tapes with both ethyltoluene and SiC powder added

We found that the addition of ethyltoluene to the starting powder of in situ processed powder-in-tube (PIT) MgB2/Fe tapes is more effective in enhancing Jc values than other hydrocarbon additions such as benzene, naphthalene and thiophene, in spite of the smaller amount of carbon substitution for the boron site. This suggests that the dominant mechanism of Jc enhancement for ethyltoluene-added tape is different from carbon substitution for boron. The addition of both ethyltoluene and SiC nanopowder to the starting powder is much more effective in increasing Jc values. This is because both mechanisms of Jc improvement—one comes from the addition of ethyltoluene and the other comes from the carbon substitution for boron by the SiC addition—work together. The highest Jc values at 4.2 K reached 320 A mm−2 in 10 T and 140 A mm−2 in 12 T for 10 mol% ethyltoluene and 10 mol% SiC-added tape.