Doping of MgB2 by nano-SiC and its potential for improvement flux pinning was studied MgB2-x(SiC)x/2 with x = 0, 0.2 0.3 a 10wt% doped samples. Co-substitution B Si C counterbalanced the effects single-element doping, decreasing Tc only 1.5K, introducing centres effective at high fields temperatures enhancing Jc Hirr significantly. Compared to non-doped sample, sample increased factor 32 5K 8T, 42 20K 5T, 14 30K 2T. At 20K, which is considered be benchmark operating temperature MgB2, best...

Since 2001, when magnesium diboride (MgB 2 ) was first reported to have a transition temperature of 39 K, conductor development has progressed where MgB superconductor wire in kilometer‐long piece‐lengths been demonstrated coil form. Now that the is available commercially, work started on demonstrating superconducting devices. This article discusses progress and development, potential for superconductors variety commercial applications: magnetic resonance imaging, fault current limiters,...

Resistive transition measurements are reported for Magnesium diboride strands with SiC dopants. The was added as 10 mol of to 90 binary magnesium diboride. Three different powders were used, the average particle sizes 200 nm, 30 and 15 nm. heat treated times ranging from 5 minutes at temperatures 675 900. Strands nm size additions had Hirr Bc2 which maximized 25.4 T 29.7 after heating 800C minutes. highest values seen a strand heated 725C 29 higher than 33

Recent advances in MgB2 conductors are leading to a new level of performance. Based on the use proper powders, chemistry, and an architecture which incorporates internal Mg diffusion (IMD), dense structure with not only high critical current density Jc, but also engineering density, Je, can be obtained. In this paper, series these advanced (or second - generation, "2G") has been prepared. Scanning electron microscopy associated energy dispersive X-ray spectroscopy were applied characterize...

Coupled magneto-optical imaging and local misorientation angle mapping have been used to demonstrate the percolative nature of supercurrent flow in YBa2Cu3O7−x(YBCO) coated conductors grown on deformation-textured Ni substrates. Barriers current occur at many YBCO grain boundaries (GBs) which propagated through buffer layers from underlying substrate, all GBs with angles >4° initiate flow. This type barrier is characteristic conductor form has found exist samples Jc(0 T,77 K) values...

We report a systematic study on the effect of sintering temperature phase formation, critical current density, upper field and irreversibility nanoscale SiC doped MgB2. Bulk Fe sheathed wires with different nano-SiC particle sizes have been made heat treated at temperatures ranging from 580 to 1000 °C. A correlation between temperature, normal state resistivity, RRR, Jc, Hc2, Hirr has found in all samples each batch. Samples sintered lower very fine well consolidated grain structure while...

We fabricated MgB2/Fe wire by a powder-in-tube (PIT) technique, using an in situ process. All samples were sintered for 30 min at different sintering temperatures ranging from 650 to 1000 °C. found strong correlations among crystallinity, critical current density (Jc), irreversibility field (Hirr), upper (Hc2), and microstructures all wires. observed that the sample with lowest temperature, ∼ °C, had larger lattice strain, Jc, change resistivity Δρ(ρ300 K–ρ40 K), Hirr, Hc2, but lower...

Cold high pressure densification, a method recently introduced at GAP in Geneva, was applied for improving the transport critical current density, Jc, and irreversibility field, Birr, of monofilamentary situ MgB2 wires tapes alloyed with 10 wt% C4H6O5 (malic acid). Tapes densified 1.48 GPa exhibited after reaction an enhancement Jc from 2 to 4 × 104 A cm−2 4.2 K/10 T 0.5 20 K/5 T, while Birr enhanced 19.3 22 K 7.5 10.0 K.

In this paper we show that an advanced internal Mg infiltration method (AIMI) is effective in producing superconducting wires containing dense MgB2 layers with high critical current densities. The in-field densities of a series AIMI-fabricated strands were investigated terms C doping levels, heat treatment (HT) time and filament numbers. highest layer Jc for our monofilamentary AIMI was 1.5 × 105 A cm−2 at 10 T, 4.2 K, when the concentration 3 mol% strand heat-treated 675 ° 4 h. Transport...

Conceptual designs of 1.5 and 3.0 T full-body magnetic resonance imaging (MRI) magnets using conduction cooled MgB

Main magnets for magnetic resonance imaging (MRI) are largely constructed with low temperature superconducting material. Most commonly used superconductors these niobium-titanium (NbTi). Such operated at 4.2 K by being immersed in a liquid helium bath long time operation. As the cost of has increased threefold last decade and market MRI systems is on average increasing more than 7% every year, there growing demand an alternative to helium. Superconductors such as magnesium-diboride (MgB2)...

Studies of the magnetic field dependence transport critical current density (Jct) and grain connectivity MgB2/Fe wires fabricated from ball-milled boron have been conducted in detail, strong correlations found, as evidenced by differences size, transition temperature, resistivity. It was observed that samples ball milling had relatively small sizes, resulting a Jct high region. On other hand, associated with poor between adjacent grains. is clearly shown reduction low related to...

Conventional doping methods that directly add C or a C-bearing species to Mg + B powder have the disadvantage of adding inhomogeneously, yielding either under-reacted regions or, in some cases, secondary phases which may be beneficial detrimental. Alternatively, pre-doped provides more homogeneous distribution dopant MgB2. In this work, powders containing varying amounts were used produce situ MgB2 strands showed high values Bc2, Birr and transport Jc (104 A cm − 2 at 13.3 T). Compared...

MgB 2 samples were prepared by using 96% boron (B) powder with strong crystalline phase that had been ball milled for various times. We observed contained ball-milled B in comparison one made from as-supplied commercial B, the results showing a significant enhancement high field critical current density (Jc) due to small grain size and better reactivity. Specifically, many boundaries MgB2 could be acting as flux pinning centers. Based on Rowell connectivity analysis, when ball-milling time...

We evaluated the effects of different boron (B) powders and malic acid (C4H6O5) addition on critical current density (Jc) mono- multi-filament MgB2 wires. found that Jc wires made from amorphous B showed best performance. Low sintering processing keeps grain size small, which leads to strong flux pinning. From transmission electron microscopy (TEM) observations, we confirmed crystalline supplied by SMI Tangshan had a β-rhombohedral structure as main phase. These two also numerous defects,...

The critical current density (Jc) was measured at 4.2 K for MgB2 strands with and without SiC additions. In some cases measurements were performed on long (1 m) samples wound barrels, the transport results being compared to of magnetic measurements. Most short in fields up 18 T. It found that situ processed 10% additions heat treated 700–800 °C showed improved irreversibility (Hr) bulk pinning strengths (Fp) as control samples; an increase Hr 1.5 T noted. Heat treatment 900 gave even larger...

The transport critical current density (Jc) was measured at 4.2 K for MgB2 monofilamentary and 7-, 19-, 37-stack multifilamentary strands. Simple, one-step heat treatments (HT) were used, with temperatures of 675 700 °C, times from 10–40 min. Most measurements performed on 1 m segments strands wound onto barrel holders. Transport properties monofilament, compared, the influence CuNi monel outer sheaths investigated. HT optimization studies various Jcs 0.8 mm OD reached 2 × 105 A cm−2 4 T (1...

Transport critical current densities and n-values were measured at 4.2 K in fields up to 15 T on 7, 19, 37-stack multifilamentary MgB 2 strands made using an in-situ route.Some included SiC additions (particle size ?30 nm), while others Mgrich compositions used.Two basic variants measured, the first had Nb filamentary barriers, second Fe barriers.All samples incorporated stabilizer form of Cu 101.Simple, one-step heat treatments used, with temperatures ranging from 700-800?C, times 10-30...

Superconducting MgB2 strands with nanometer-scale SiC additions have been investigated systematically using transport and magnetic measurements. A comparative study of different nano-SiC addition levels has shown C-doping-enhanced critical current density Jc through enhancements in the upper field, Hc2, decreased anisotropy. The flux pinning force obtained from measurements were found to greatly differ values measurements, particularly regards field dependence. differences results are...

A series of MgB2 superconducting composite strands co-doped with Dy2O3 and C were prepared via an advanced internal Mg infiltration (AIMI) route.The transport properties layer growth studied in terms the doping level, reaction temperature, time. Transport studies showed that both critical current densities, Jcs, irreversibility fields, Birrs, increased doping. The highest Jc was 1.35 x 10^5 A/cm2 at 4.2 K, 10 T, 30% higher than best AIMI wires without "non-barrier" reached 3.6 10^4 which...