High critical current density in Ti-doped MgB[sub 2]/Ta/Cu tape by powder-in-tube process.

Ti-doped MgB[sub 2]/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 TiB[sub 2] phase was formed in Ti-doped MgB[sub 2] tape. Magnetization measurement results show that the critical transition temperature of MgB[sub 2]/Ta/Cu tape with Ti doping is around 38 K. The irreversibility field H[sub irr] and critical current density J[sub c] can be greatly enhanced by Ti doping. H[sub irr] of the Mg[sub 0.9]Ti[sub 0.1]B[sub 2] tape is as high as 7.4 T at 10 K. The high critical current density J[sub c] of 1.5 × 10[sup 6] A/cm² (10 K, self field) and 9.3 × 10[sup 5] A/cm² (20 K, self field) are obtained in the Mg[sub 0.9]Ti[sub 0.1]B[sub 2] tape. In addition, a suitable amount of Ti doping can lead to a high density and fine grain size of MgB[sub 2], which may be the reason for high J[sub c] in Ti-doped MgB[sub 2] tapes. [ABSTRACT FROM AUTHOR]