Effects of three different homemade nanocarbons doping on the superconducting properties of MgB2 tapes

• Homemade carbon additions led to significant enhancement of the supercurrent.
• HCB-doped tapes exhibited the best Jc–B values.
• The Jc–B property of CNT-doped samples was less influenced by sintering temperature.

The doping effects of three different homemade nanocarbons on microstructure and superconducting properties of in situ powder-in-tube (PIT) processed MgB2/Fe tapes were studied. Compared with pure tapes, all homemade nano-carbon additions led to an order of magnitude enhancement of the supercurrent at 4.2 K, 10 T. Among them, hollow carbon nanoboxes doped samples exhibited the highest transport Jc–B properties, about 3.4 × 104 A cm−2 at 4.2 K, 10 T (Je ∼ 104 A cm−2). The large Jc improvements of doped samples are thought to be attributed to the enhancement of flux pinning force. It is also interesting that the change of microstructure and critical field of three nanocarbons doped MgB2 samples are not obvious, which mainly because that the performance parameters of these nanocarbons with different morphologies are almost same.