扩散法制备CNTs掺杂的MgB2超导块材

采用扩散法制备高Jc的MgB2超导块材，将制备样品的超导性能与传统固相反应法制备CTNs掺杂的MgB2超导块材的性能做详细对比。研究发现，所采用的新型扩散方法可以有效地提高MgB2块材的密度，减少原料Mg粉中氧的不利影响，该法制备的MgB2块材更为均匀，MgO杂相较少，从而可以在自场下得到较高的临界电流密度，但在高场下性能提高并不明显，而CNTs掺杂可以有效改善扩散法制备的样品在高场下性能较差的弱点。CNTs掺杂量为0.5%（质量分数）的样品，在10 K，4 T条件下，Jc仍有1.0×104 A/cm2，在零场下更达到了0.46 MA/cm2，比在相同条件下用固相反应法制备的样品要高2~3倍。

Doping Effect of CNTs on Superconductivity of MgB2 Bulks Prepared by a Diffusion Method

High Jc MgB2 superconducting bulks doped with carbon nano-tubes (CNTs) were prepared by a diffusion method, and their superconductivity was compared with that of CNTs-doped MgB2 prepared by a conventional solid-state reaction method. Results show that the novel diffusion method can increase the density of MgB2 bulks remarkably and reduce the adverse effect of oxygen in Mg powder. The MgB2 bulks prepared by the diffusion method are more uniform with less MgO impurity, so that they have higher critical current density in the self field. But the properties are improved a little in high field; however, MgB2 can overcome the shortcomings in high-field notably by CNTs doping. For the MgB2- sample with 0.5% CNTs doping under the condition of 10 K and 4 T, Jc is as high as 1.0×104 A/cm2 and it reaches 0.46 MA/cm2 in zero field, which is 2 to 3 times higher than that of the MgB2 samples by the solid-state reaction under the same condition.