Centre d'études et d'expertise sur les risques, l'environnement, la mobilité et l'aménagement

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A high-purity MgB 4 phase has been synthesized and used as the precursor powder for the realization of in situ wires. Various final heat treatments, from 550 to 1100 • C for 20 min each, have been carried out to convert the inner mixture to MgB 2 . Critical current densities up to 1.75 × 10 6 and 0.98 × 10 6 A cm −2 at 4.2 and 20 K, with 0.2 T, up to 0.76 × 10 5 A cm −2 at 4.2 K and 4 T, and up to 0.78 × 10 5 A cm −2 at 20 K and 2 T were measured. Critical temperatures up to 38.5 K were measured. These results suggest that this could be a good alternative to both ex situ and classical in situ routes.