Large critical current density in MgB₂wire using MgB₄as precursor

Abstract

A high-purity MgB4
\nphase has been synthesized and used as the precursor powder for the
\nrealization of in situ wires. Various final heat treatments, from 550 to 1100 ◦C for 20 min each,
\nhave been carried out to convert the inner mixture to MgB2
\n. Critical current densities up to
\n1.75 × 106
\nand 0.98 × 106 A cm−2
\nat 4.2 and 20 K, with 0.2 T, up to 0.76 × 105 A cm−2
\nat
\n4.2 K and 4 T, and up to 0.78 × 105 A cm−2
\nat 20 K and 2 T were measured. Critical
\ntemperatures up to 38.5 K were measured. These results suggest that this could be a good
\nalternative to both ex situ and classical in situ routes.