Two sets of MgB2 samples doped with up to 5at%Al were prepared in different laboratories using various procedures. Decreases in the a and c lattice parameters were observed with Al doping, confirming Al substitution at the Mg site. The critical temperature remained largely unchanged with Al doping. For 1–2.5at% doping, at 20K the in-field critical current densities were enhanced; particularly at lower fields. At 5K, the in-field JC was markedly improved; for example JC at 5T was enhanced by a factor of 20 for a doping level of 1at%Al. The improved JC values were correlated with an increased sample resistivity, which was indicative of an increase in the upper critical field, HC2, through alloying.

Enhancement of Critical Current Density in Low Level Al-Doped MgB2. A.Berenov, A.Serquis, X.Z.Liao, Y.T.Zhu, D.E.Peterson, Y.Bugoslavsky, K.A.Yates, M.G.Blamire, L.F.Cohen, J.L.MacManus-Driscoll: Superconductor Science and Technology, 2004, 17, 1093-6