We report on the transport and magnetization properties of MgB2 wires fabricated by a powder-in-tube (PIT) technique. Temperature and magnetic-field-dependent resistivity displays a high conductivity and upper critical field Hc2 generally observed in dense samples. The electronic mass anisotropy γ≈1.3±0.15 predicts some texturing in the wire. Our data on transition temperature TC, Hc2, and both magnetic and transport critical current density Jc indicate that MgB2 can be manufactured in a wire form using a PIT technique and required engineering Jc can be achieved on further optimization.

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Ti-doped MgB2/Cu tapes with Ta as a buffer layer were prepared through the in situ powder in tube method by using Mg, Ti, and B powders. The phase compositions, microstructure features, and superconducting properties were investigated by x-ray diffraction, scanning electron microscope, and superconducting quantum interference device magnetometer. It is found that TiB2 phase was formed in Ti-doped MgB2 tape. Magnetization measurement results show that the critical transition temperature of MgB2/Ta/Cu tape with Ti doping is around 38 K. The irreversibility field Hirr and critical current density Jc can be greatly enhanced by Ti doping. Hirr of the Mg0.9Ti0.1B2 tape is as high as 7.4 T at 10 K. The high critical current density Jc of 1.5×106 A/cm2 (10 K, self field) and 9.3×105 A/cm2 (20 K, self field) are obtained in the Mg0.9Ti0.1B2 tape. In addition, a suitable amount of Ti doping can lead to a high density and fine grain size of MgB2, which may be the reason for high Jc in Ti-doped MgB2 tapes.

Using X‐ray diffraction (XRD), scanning electron microscope (SEM), and differential scanning calorimetry (DSC), we have investigated the reaction between MgB4 and Mg in its solid, liquid, and gas physical states. The XRD results indicate that the reaction of MgB4+Mg=2MgB2 always occurs independently of the different states of Mg. DSC measurements show that the solid–solid reaction MgB4(s)+Mg(s)=2MgB2(s), the Mg melting Mg(s)→Mg(l), and the Mg volatilization occur in turn with increasing temperature for mixed (MgB4+Mg) powder with a nominal stoichiometry of MgB2. SEM observations indicate that the resulting synthesized MgB2 samples, obtained from the MgB4+Mg mixtures, have a denser microstructure than those obtained directly from Mg+B mixtures. On the basis of XRD, DSC, and SEM results, a kinetic model for the reaction between MgB4 and Mg is proposed.