Critical current densities of powder-in-tube MgB2 tapes fabricated with nanometer-size Mg powder

Yamada, Hideyuki; Hirakawa, M.; Kumakura, Hiroaki; Matsumoto, Akiyoshi; Kitaguchi, Hitoshi

doi:10.1063/1.1667263

Cited by 86 publications

(59 citation statements)

References 10 publications

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“…Yamada et al reported that the small MgB 2 grain size was effective in enhancing flux pinning because the grain boundaries of MgB 2 represented effective pinning centers, as in the case of A15 metallic superconductors. 25 Fischer et al fabricated MgB 2 wires and bulks by a mechanical alloying method. 30 They obtained one of the highest J c values without any other element materials added.…”

Section: Results and Disscussionmentioning

confidence: 99%

The doping effect of multiwall carbon nanotube on MgB2∕Fe superconductor wire

Kim

Yeoh

Qin

et al. 2006

Journal of Applied Physics

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We evaluated the doping effect of two types of multiwall carbon nanotubes ͑CNTs͒ with different aspect ratios on MgB 2 / Fe monofilament wires. Relationships between microstructure, magnetic critical current density ͑J c ͒, critical temperature ͑T c ͒, upper critical field ͑H c2 ͒, and irreversibility field ͑H irr ͒ for pure and CNT doped wires were systematically studied for sintering temperature from 650 to 1000°C. As the sintering temperature increased, T c for short CNT doped sample slightly decreased, while T c for long CNT doped sample increased. This indicates better reactivity between MgB 2 and short CNT due to its small aspect ratio, and substitution of carbon ͑C͒ from short CNT for boron ͑B͒ occurs. In addition, short CNT doped samples sintered at high temperatures of 900 and 1000°C exhibited excellent J c , and this value was approximately 10 4 A/cm 2 in fields up to 8 T at 5 K. This suggests that short CNT is a promising carbon source for MgB 2 superconductor with excellent J c . In particular, inclusion of nanosized MgO particles and substitution of C into the MgB 2 lattice could result in strong flux pinning centers.

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Section: Results and Disscussionmentioning

confidence: 99%

The doping effect of multiwall carbon nanotube on MgB2∕Fe superconductor wire

Kim

Yeoh

Qin

et al. 2006

Journal of Applied Physics

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“…Up to now, the highest J c values at temperatures of 5 -20 K in magnetic fields above 3 T have been achieved by doping with SiC nanoparticles; 2 but other factors, such as the decrease of grain size, are also effective in increasing J c at high fields. 3 The poor electrical connectivity between grains, porosity, and the presence of secondary phases are among the main restricting factors for J c , even in low fields, and their influence can easily exceed the benefits of having effective pinning centers in high fields.…”

Section: Introductionmentioning

confidence: 99%

Flux pinning force in bulkMgB2with variable grain size

et al. 2007

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We report temperature and magnetic-field dependence of flux pinning force in bulk MgB 2 with variable grain size. The samples are prepared by advanced methods, allowing minimizing effects of porosity, impurities, and inclusions of secondary phases. The effects of grain connectivity, flux-creep phenomena, and grain size on critical current density and flux pinning curves are analyzed. We have compared the field dependence of the pinning force for a range of samples with the predictions of theoretical models accounting for the effect of the grain size. There is qualitative agreement between grain-boundary pinning mechanism proposed by Hampshire and Jones ͓J. Phys. C 21, 419 ͑1987͔͒ and the experimentally observed grain-size dependence of pinning force in bulk MgB 2 .

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“…They include, for example, the ball-milling method 4,5 , the addition of nanometer-size SiC powder 6 , the use of MgH 2 powder instead of Mg powder 7 , and the use of nanometer-size Mg powder 8 . The addition of nanometer-size…”

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confidence: 99%

Effect of aromatic hydrocarbon addition onin situpowder-in-tube processed MgB₂tapes

Yamada

Hirakawa

Kumakura

et al. 2006

Supercond. Sci. Technol.

154

102

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We fabricated in situ powder-in-tube processed MgB 2 /Fe tapes using aromatic hydrocarbon of benzene, naphthalene, and thiophene as additives, and investigated the superconducting properties. We found that these aromatic hydrocarbons were very effective for increasing the Jc values. The Jc values of 20mol% benzene-added tapes reached 130A/mm 2 at 4.2K and 10T. This value was almost comparable to that of 10mol% SiC -added tapes and about four times higher than that of tapes with no additions.Microstructure analyses suggest that this Jc enhancement is due to both the substitution of carbon for boron in MgB 2 and the smaller MgB 2 grain size.The MgB 2 superconductor is expected to be applied to practical superconducting wires because its transition temperature, 39K, is much higher than those of conventional metallic superconductors.The lower cost of the raw materials, Mg and B, than that of Nb, is an additional advantage of MgB 2 .Recently, small coils using MgB 2 wires have been produced. In order to evaluate the potential of MgB 2 for power applications, wire processing techniques are now being actively developed throughout the world. The most popular method is the so-called in situ powder-in-tube (PIT) method,

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Critical current densities of powder-in-tube MgB2 tapes fabricated with nanometer-size Mg powder

Cited by 86 publications

References 10 publications

The doping effect of multiwall carbon nanotube on MgB2∕Fe superconductor wire

The doping effect of multiwall carbon nanotube on MgB2∕Fe superconductor wire

Flux pinning force in bulkMgB2with variable grain size

Effect of aromatic hydrocarbon addition onin situpowder-in-tube processed MgB₂tapes

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Critical current densities of powder-in-tube MgB2 tapes fabricated with nanometer-size Mg powder

Cited by 86 publications

References 10 publications

The doping effect of multiwall carbon nanotube on MgB2∕Fe superconductor wire

The doping effect of multiwall carbon nanotube on MgB2∕Fe superconductor wire

Flux pinning force in bulkMgB2with variable grain size

Effect of aromatic hydrocarbon addition onin situpowder-in-tube processed MgB2tapes

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Effect of aromatic hydrocarbon addition onin situpowder-in-tube processed MgB₂tapes