Fabrication and superconducting properties of internal Mg diffusion processed MgB₂wires using MgB₄precursors

Abstract

Monofilament MgB2/Nb/Monel wires were fabricated using three different MgB4 precursors by an internal Mg diffusion (IMD) process. The wire geometry and heat-treatment conditions were optimized in order to improve the critical current density (Jc) of the MgB2 wire. The influences of the quality of MgB4 powders, such as the particle size and MgO impurity, on the microstructure and superconducting properties of the wires were discussed. Although there were small amounts of voids, unreacted MgB4 particles and MgO impurity existed in the superconducting layers, and the transport layer Jc of the wire with the MgB4 precursor reached 3.0 × 104 A cm−2 at 4.2 K and 10 T, which was comparable to that of IMD-processed wires fabricated using boron precursors. Both the non-barrier Jc and engineering Jc of MgB2 wire made using a MgB4 precursor were enhanced due to the improved grain connectivity and the enlarged fill factor.

Flux Pinning and Superconducting Properties of Bulk MgB2 with MgB4 Addition

“…Therefore, we concluded that adding MgB 4 externally is a safer way to get the best performance than producing it in situ. Several researchers created MgB 4 employing a diffusion technique . In this work, we tried to synthesize MgB 4 separately and sinter its tiny amounts together with the MgB 2 powder.…”

“…Several researchers created MgB 4 employing a diffusion technique. [14][15][16][17][18] In this work, we tried to synthesize MgB 4 separately and sinter its tiny amounts together with the MgB 2 powder. Here, pinning performance of such a MgB 2 bulk composite is discussed in detail.…”

The effect of boron powder on the microstructure of MgB2filaments prepared by the modified internal magnesium diffusion technique

“…Thus, other techniques have been developed to try to increase the density of the MgB 2 [1][2][3]. Among them, the internal magnesium diffusion (IMD) technique was successfully employed, resulting in wires with an increased critical current density, J c , in the superconducting layers [4][5][6].…”