Hollow carbon spheres as an efficient dopant for enhancing the critical current density of MgB<sub>2</sub>-based tapes

Gao, Zhaoshun; Ma, Yanwei; Zhang, Xianping; Wang, Dongliang; Wang, Junhong; Awaji, Satoshi; Watanabe, Kazuo; Liu, Boyang

doi:10.1088/0953-2048/21/10/105020

Cited by 13 publications

(9 citation statements)

References 28 publications

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“…Over the last 10 years, many research groups have made significant progress in improving the in-field J c of MgB 2 [9,10]. The addition of SiC [11][12][13], C [12,14], or B 4 C [15,16], doping with carbon nanotubes [17] or hollow carbon spheres [18], and increasing the sample packing density [19] are effective methods for improving J c . To date, it is confirmed that doping with carbon or carbon-based compounds is the best way to enhance the current-carrying capability of MgB 2 superconductor.…”

Section: Introductionmentioning

confidence: 99%

In situsynthesis and current-carrying characteristics of superconducting MgB₂–B₄C composites with MgB₂fractions ranging from 18% to 85%

Zhang

Xue

Bai

et al. 2012

Supercond. Sci. Technol.

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Carbon is known to be the most effective dopant to enhance the high-field current-carrying capacity for high-power applications of MgB2 superconductors. Using B4C instead of B to synthesize MgB2 will be expected to produce superconducting MgB2 together with in situ carbon doping. By using just two reaction substances, B4C and Mg, superconducting MgB2–B4C composites with MgB2 fractions ranging from 18 to 85% were fabricated successfully by solid-state reaction. The influence of the grain size of the B4C raw material on the critical current density (Jc), the fraction of MgB2, and the critical transition temperature (Tc) of MgB2–B4C composites were investigated. Tc, Jc, and the fraction of MgB2 were increased with decrease in the grain size of the B4C raw material. Compared with a pure MgB2 superconductor, the critical transition temperature of the MgB2 composites fabricated with small B4C grain size was suppressed slightly, but the in-field current-carrying capacity was improved significantly. By using B4C raw material with a grain size of 2.5 μm, the resultant superconducting composite showed a critical transition temperature of 33.0 K, a high self-field Jc of 0.7 × 106 A cm−2, and a remarkable in-field current density value of 1 × 104 A cm−2 under 6 T at 10 K. These results indicate that the composites can be applied directly in high-power applications of superconductors. The enhancement of flux pinning in the superconducting MgB2–B4C composite is discussed and considered to be mainly due to the increment in the effective surface area of grain boundaries per unit volume.

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Section: Introductionmentioning

confidence: 99%

In situsynthesis and current-carrying characteristics of superconducting MgB₂–B₄C composites with MgB₂fractions ranging from 18% to 85%

Zhang

Xue

Bai

et al. 2012

Supercond. Sci. Technol.

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“…When a compound with C is doped into , the C substitutes for B, thus introducing scattering that reduces electron mean free path and coherence length of the superconductor and hence increases the [19]. Simultaneously, the dopants effectively enhance pinning strength by introducing lattice distortion and new grain boundaries [20], [21].…”

Section: Introductionmentioning

confidence: 99%

Comparison on Effects of ${\rm B}_{4}{\rm C}$, ${\rm Al}_{2}{\rm O}_{3}$, and SiC Doping on Performance of ${\rm MgB}_{2}$ Conductors

Viljamaa

Kulich

Kòváč

et al. 2011

IEEE Trans. Appl. Supercond.

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Several MgB 2 monofilamentary samples are prepared to evaluate the effects that the doping compounds B 4 C, Al 2 O 3 , and SiC have on critical current density ( c ) and the c dependency of magnetic flux density ( ) of the sample. All of the samples in this study have Nb sheaths and are manufactured using in situ precursor powders and the Powder-in-Tube fabrication method. The amounts of added impurities are 10 wt.% for B 4 C and Al 2 O 3 , and 3, 10, and 20 wt.% for SiC. A reference sample without any doping is also prepared. All of the samples are heat treated between 650 and 800 C for 30 minutes. The transport c ( ) characteristics are measured at 4.2 K and the magnetic c ( ) behavior is obtained in varied temperatures up to 30 K.The changes in connectivity, or effective cross-section, are also evaluated by performing resistivity measurements on the samples after removal of the sheath. Furthermore, the pinning forces of the samples are evaluated from the magnetic measurements.Index Terms-Connectivity, current density, heat treatment, impurity addition, magnetic field effects, MgB 2 .

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“…Owing to the strong links among MgB 2 grains, there is no much influence on its superconductivity when a sample was contaminated or doped by a small ratio. Experimental results reported by Wang's group (Wang et al, 2004) and Ma's group (Ma et al, 2006;Gao et al, 2008) showed that the critical current density and flux pinning in some doping were enhanced evidently. Several papers suggested also that there was no appreciable difference between a perfect MgB 2 sample and one with MgO or oxygen contamination, but the flux pinning was improved Przybylski et al, 2003;Zeng et al, 2001;Liao et al, 2003).…”

Section: Compound Superconductorsmentioning

confidence: 89%

MgB2-MgO Compound Superconductor

Zhang¹,

Zhou²

2010

Superconductor

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Hollow carbon spheres as an efficient dopant for enhancing the critical current density of MgB₂-based tapes

Cited by 13 publications

References 28 publications

In situsynthesis and current-carrying characteristics of superconducting MgB₂–B₄C composites with MgB₂fractions ranging from 18% to 85%

In situsynthesis and current-carrying characteristics of superconducting MgB₂–B₄C composites with MgB₂fractions ranging from 18% to 85%

Comparison on Effects of ${\rm B}_{4}{\rm C}$, ${\rm Al}_{2}{\rm O}_{3}$, and SiC Doping on Performance of ${\rm MgB}_{2}$ Conductors

MgB2-MgO Compound Superconductor

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Hollow carbon spheres as an efficient dopant for enhancing the critical current density of MgB2-based tapes

Cited by 13 publications

References 28 publications

In situsynthesis and current-carrying characteristics of superconducting MgB2–B4C composites with MgB2fractions ranging from 18% to 85%

In situsynthesis and current-carrying characteristics of superconducting MgB2–B4C composites with MgB2fractions ranging from 18% to 85%

Comparison on Effects of ${\rm B}_{4}{\rm C}$, ${\rm Al}_{2}{\rm O}_{3}$, and SiC Doping on Performance of ${\rm MgB}_{2}$ Conductors

MgB2-MgO Compound Superconductor

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Hollow carbon spheres as an efficient dopant for enhancing the critical current density of MgB₂-based tapes

In situsynthesis and current-carrying characteristics of superconducting MgB₂–B₄C composites with MgB₂fractions ranging from 18% to 85%

In situsynthesis and current-carrying characteristics of superconducting MgB₂–B₄C composites with MgB₂fractions ranging from 18% to 85%