Recently, an international PCT patent, entitled as “MgB2 material containing carbon and its preparation method”, was applied by the key laboratory of superconductivity. Within the search scope of the state intellectual property office in china, this work has novelty and practicability even in the world. If the authorization is obtained at last, it will be a very valuable intellectual property for the preparation of the long MgB2 tapes and wires with high superconducting property.
It is found that if some nano-carbon particles are added in the mixing process of Mg and boron powders, C can be substituted into MgB2 lattice, and the grain connectivity can be improved at the same time. As proved by many experiments, the substitution of boron by carbon could introduce a net of intragranular defects due to crystal lattice distortions and local fluctuations of the superconducting order parameter. Both of them can strongly improve the pinning properties of MgB2. Consequently, the Jc-B properties of MgB2 tapes and wires can be significantly improved by carbon doping.
With this preparation method, MgB2 tapes and wires will be a promising candidate for engineering applications in the temperature range 20-30 K, especially for the use of MRI magnet.