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A significant enhancement of Jc and Hirr in MgB2 tapes has been achieved by the in situ powder-in-tube method utilizing hollow carbon spheres (HCS) as dopants. At 4.2 K, the transport Jc for the 850C sintered samples reached 3.1x10^4, and 1.4x10^4 A/cm^2 at 10 and 12 T, respectively, and were better than those of optimal nano-SiC doped tapes. Furthermore, the Hirr for doped sample was raised up to 16.8 T at 10 K due to the carbon substitution effect. The results demonstrate that HCS is one of the most promising dopants besides nano-carbon and SiC for the enhancement of current capacity for MgB2 in high fields.
Ex-situ Powder-In-Tube MgB2 tapes prepared with ball-milled, undoped powders showed a strong enhancement of the irreversibility field H*, the upper critical field Hc2 and the critical current density Jc(H) together with the suppression of the anisotr
The effect of the quality of starting powders on the microstructure and superconducting properties of in-situ processed Fe-sheathed MgB2 tapes has been investigated. Three different types of commercial atomized spherical magnesium powder and two diff
MgB2/Fe tapes with 2.5-15 at.% ZrB2 additions were prepared through the in situ powder-in-tube method. Compared to the pure tape, a significant improvement in the in-field critical current density Jc was observed, most notably for 10 at.% doping, whi
The high resistivity of many bulk and film samples of MgB2 is most readily explained by the suggestion that only a fraction of the cross-sectional area of the samples is effectively carrying current. Hence the supercurrent (Jc) in such samples will b
The DC magnetization and AC complex magnetic susceptibilities were measured for MgB2 single crystals, unsubstituted and carbon substituted with the composition of Mg(B_0.94C_0.06)2. The measurements were performed in AC and DC magnetic fields oriente