Influence of crystalline boron powders on superconducting properties of C-doped internal Mg diffusion processed MgB₂wires

Abstract

Monofilament MgB 2 /Fe wires or tapes were fabricated with two different purity crystalline boron powders, using internal magnesium diffusion (IMD) and in situ powder-in-tube (PIT) processes. To evaluate which method was more insensitive to the purity of the boron powders, a sensitivity factor was used. It was found that the IMD process was less sensitive to the purity of the boron powders, compared to the PIT method. Furthermore, J c values of the IMD-processed wires were higher than those of the PIT-processed samples. The reduced porosity and hence the increased density in the IMD-processed samples was thought to be the main reason. Although a number of B-rich particles remained in the MgB 2 region, a layer J c as high as 4.8×10 4 A cm −2 at 4.2 K and 10 T was still obtained in the IMD-processed wire, which was comparable to that of IMD-processed wires fabricated using amorphous boron powders.

Formation of High-Field Pinning Centers in Superconducting MgB2 Wires by Using High Hot Isostatic Pressure Process

“…The MgB 2 material structure is also influenced by chemical doping [2,13], the purity level of the components [14], and the particle size of the precursor powders [15]. Doping in the MgB 2 material is used to produce additional flux pinning centers in the MgB 2 structure.…”

Microstructure and superconducting properties of nanocarbon-doped internal Mg diffusion-processed MgB2wires fabricated using different boron powders

“…Li et al pushed the J c of MgB 2 wires up to 1.35×10 5 A cm −2 at 4.2 K and 10 T using a similar process called advanced internal Mg infiltration, combining nano Dy 2 O 3 and co-doped C [33][34][35]. Our group also followed the IMD process and obtained MgB 2 wires with a layer J c of 4.8×10 4 A cm −2 at 4.2 K and 10 T using crystalline boron powders [36]. Therefore, the IMD process gives us a possibility of obtaining a higher J c and even an J e which are both important for applications.…”

“…The superconducting properties of MgB 2 wires and tapes are strongly affected by the characteristics of precursor boron powders, such as structure, morphology, particle size and purity [17,[36][37][38][39]. The investigation of MgB 2 wires fabricated with various crystalline and amorphous boron (AB) precursors has been presented in several works.…”

“…The investigation of MgB 2 wires fabricated with various crystalline and amorphous boron (AB) precursors has been presented in several works. It was found that high-performance MgB 2 wires in high fields can be fabricated using coarse Mg powders [40] and crystalline boron nanopowders [36,38], and the highest J c in low fields can be obtained by fabricating MgB 2 wires using AB powders [37]. However, the influence of the quality of boron powders on the superconducting performance for the IMD-processed MgB 2 wires has not been studied in depth.…”

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

“…Li et al pushed the layer J c of MgB 2 wires up to 1.35×10 5 A cm −2 (4.2 K, 10 T), and the engineering critical current density ( J e ) up to 1.67×10 4 A cm −2 (4.2 K, 10 T) using a similar process called advanced internal Mg infiltration (AIMI) [21][22][23][24]. Our group also followed the IMD process and obtained MgB 2 wires with a J c layer of 4.8×10 4 A cm −2 (4.2 K, 10 T) using crystalline boron powders [25,33,34]. In all, the IMD process offers the possibility of obtaining MgB 2 wires with higher J c , even higher J e , which is important for practical applications.…”