The influence of the nature of the boron precursor on the superconducting properties of polycrystalline MgB 2 was studied. Critical current densities (J c 's) for the MgB 2 made from high purity amorphous boron are at least a factor of three higher than typical values measured for standard MgB 2 samples made from amorphous precursors. Two possible mechanisms are proposed to account for this difference. Samples made from crystalline boron powders have around an order of magnitude lower J c 's compared to those made from amorphous precursors. X-ray, T c and resistivity studies indicate that this is as a result of reduced current cross section due to the formation of (Mg)B-O phases. The samples made from amorphous B contain far fewer Mg(B)-O phases than crystalline B despite the fact that the amorphous B contains more B 2 O 3 . The different reactivity rates of the precursor powders accounts for this anomaly.

Intense vortex pinning enhanced by semicrystalline defect traps in self-aligned nanostructured MgB2 0.5-5.0 wt % Dy 2 O 3 was in situ reacted with Mg+ B to form pinned MgB 2 . While T c remained largely unchanged, J c was strongly enhanced. The best sample ͑only 0.5 wt % Dy 2 O 3 ͒ had a J c ϳ 6.5ϫ 10 5 A cm −2 at 6 K, 1 T and 3.5ϫ 10 5 A cm −2 at 20 K, 1 T, around a factor of 4 higher compared to the pure sample, and equivalent to hot-pressed or nano-Si-added MgB 2 at ഛ1 T. Even distributions of nanoscale precipitates of DyB 4 and MgO were observed within the grains. The room temperature resistivity decreased with Dy 2 O 3 indicative of improved grain connectivity.

Bulk Mn-doped Cu2O samples were produced by reacting Cu2O and Mn2O3 powders in Ar gas at 650 and 800°C to give a nominal composition of 1.7at.% Mn-doped Cu2O. From x-ray energy dispersive spectrum analysis, the actual doping level was lower at 0.3–0.5at.% Mn. Room temperature ferromagnetism with a coercive field of 50Oe was found in the 650°C samples. The Curie temperature (TC) of samples sintered at 650°C was above 300K, whereas for 800°C samples it was 215±5K. Using the nominal doping level, the magnetization saturation value was calculated to be ∼0.4μB∕Mn at 10K.

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The rapid progress on MgB 2 superconductor since its discovery [1] has made this material a strong competitor to low and high temperature superconductors (HTS) for applications with a great potential to catch the niche market such as in magnetic resonant imaging (MRI). Thanks to the lack of weak links and the two-gap superconductivity of MgB 2 [2,3] a number of additives have been successfully used to enhance the critical current density, J c and the upper critical field, H c2 . [4][5][6][7][8][9][10][11][12] Carbon nanotubes (CNTs) have unusually electrical, mechanical and thermal properties [13][14][15][16] and hence is an ideal component to fabricate composites for improving their performance. To take advantages of the extraordinary properties of CNTs it is important to align CNTs in the composites.Here we report a method of alignment of CNTs in the CNT/MgB 2 superconductor composite wires through a readily scalable drawing technique. The aligned CNT doped MgB 2 wires show an enhancement in magnetic J c (H) by more than an order of magnitude in high magnetic fields, compared to the undoped ones. The CNTs have also significantly enhanced the heat transfer and dissipation. CNTs have been used mainly in structural materials, but here the advantage of their use in functional composites is shown and this has wider ramifications for other functional materials.