Stoichiometry dependence of superconductivity and microstructure in mechanically alloyed MgB2

Perner, O.; Eckert, J.; Häßler, Wolfgang; Fischer, C.; Acker, Jörg; Gemming, Thomas; Fuchs, G.; Holzäpfel, B.; Schultz, L.

doi:10.1063/1.1861142

Cited by 37 publications

(35 citation statements)

References 9 publications

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“…The former employs powder starting materials [27], whereas the latter employs a powder of synthesized superconducting material [28]. The superconducting properties of PIT-processed MgB 2 conductors are very sensitive to the quality of the starting powder [29][30][31][32][33], particle size [34][35][36], porosity of the MgB 2 core [37,38], heat treatment temperature [34,[39][40][41], and the sheath material [27,42]. In general, ex situprocessed MgB 2 tapes show lower J c than in situ-processed tapes.…”

Section: Powder-in-tube Processmentioning

confidence: 99%

MgB2 coated superconducting tapes with high critical current densities fabricated by hybrid physical–chemical vapor deposition

Ranot

Kang

2012

Current Applied Physics

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The MgB 2 coated superconducting tapes have been fabricated on textured Cu (0 0 1) and polycrystalline Hastelloy tapes using coated conductor technique, which has been developed for the second generation high temperature superconducting wires. The MgB 2 /Cu tapes were fabricated over a wide temperature range of 460-520 °C by using hybrid physical-chemical vapor deposition (HPCVD) technique. The tapes exhibited the critical temperatures (T c ) ranging between 36 and 38 K with superconducting transition width (∆T c ) of about 0.3-0.6 K. The highest critical current density (J c ) of 1.34 × 10 5 A/cm 2 at 5 K under 3 T is obtained for the MgB 2 /Cu tape grown at 460 ºC. To further improve the flux pinning property of MgB 2 tapes, SiC is coated as an impurity layer on the Cu tape. In contrast to pure MgB 2 /Cu tapes, the MgB 2 on SiC-coated Cu tapes exhibited opposite trend in the dependence of J c with growth temperature. The improved flux pinning by the additional defects created by SiC-impurity layer along with the MgB 2 grain boundaries lead to strong improvement in J c for the MgB 2 /SiC/Cu tapes. The MgB 2 /Hastelloy superconducting tapes fabricated at a temperature of 520 °C showed the critical temperatures ranging between 38.5 and 39.6 K. We obtained much higher J c values over the wide field range for MgB 2 /Hastelloy tapes than the previously reported data on other metallic substrates, such as Cu, SS, and Nb. The J c values of J c (20 K, 0 T) ~5.8 × 10 6 A/cm 2 and J c (20 K, 1.5 T) ~2.4 × 10 5 A/cm 2 is obtained for the 2-µm-thick MgB 2 /Hastelloy tape. This paper will review the merits of coated conductor approach along with the HPCVD technique to fabricate MgB 2 conductors with high T c and J c values which are useful for large scale applications.

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Section: Powder-in-tube Processmentioning

confidence: 99%

MgB2 coated superconducting tapes with high critical current densities fabricated by hybrid physical–chemical vapor deposition

Ranot

Kang

2012

Current Applied Physics

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“…Recently, MA has been used to produce various kinds of materials, such as QC, amorphous alloys, rare-earth permanent magnet materials, superconducting materials and intermetallic compounds [12][13][14][15]. MA offers special advantages of extending the compositional range of QC as compared with the stable QC phase which usually has a narrow compositional range [16].…”

Section: Introductionmentioning

confidence: 99%

Formation of AlCuFe icosahedral quasicrystal by mechanical alloying: XAFS and XRD studies

Yin

Xie

Bian

et al. 2008

Journal of Alloys and Compounds

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“…2) displays the characteristic temperature dependence of MgB 2 with a low ratio of the residual (R just above T c ) and room temperature resistance, RRR=1.38, which is typical for MgB 2 samples with a high concentration of defects or impurities [15]. Enhanced scattering at the grain boundaries should also contribute to an increase of the residual resistance and lower the RRR-values.…”

Section: Resultsmentioning

confidence: 99%

Superconducting properties of nanocrystalline MgB₂

Lorenz¹,

Perner²,

Eckert³

et al. 2006

Supercond. Sci. Technol.

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Abstract. Nanocrystalline MgB 2 produced by mechanical alloying has been shown to exhibit enhanced superconducting properties such as increased pinning and higher critical currents. However, the effects of the synthesis process on the intrinsic superconducting properties have not been addressed yet. We have investigated the superconducting gap structure of nanocrystalline MgB 2 pellets synthesized by highenergy ball milling employing specific heat measurements. We found that the larger σ-gap decreased whereas the smaller π-gap slightly increased in ball milled MgB 2 as compared to bulk samples synthesized along the standard routes. The data show that the ball milling process introduces defects that enhance the interband scattering similar to irradiation with neutrons. The reduction of the σ-gap explains the lower superconducting transition temperature of 33 K.

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Stoichiometry dependence of superconductivity and microstructure in mechanically alloyed MgB2

Abstract: Articles you may be interested inDependence of magnetoelectric properties on sintering temperature for nano-SiC-doped MgB2/Fe wires made by combined in situ/ex situ process

Cited by 37 publications

References 9 publications

MgB2 coated superconducting tapes with high critical current densities fabricated by hybrid physical–chemical vapor deposition

MgB2 coated superconducting tapes with high critical current densities fabricated by hybrid physical–chemical vapor deposition

Formation of AlCuFe icosahedral quasicrystal by mechanical alloying: XAFS and XRD studies

Superconducting properties of nanocrystalline MgB₂

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Stoichiometry dependence of superconductivity and microstructure in mechanically alloyed MgB2

Abstract: Articles you may be interested inDependence of magnetoelectric properties on sintering temperature for nano-SiC-doped MgB2/Fe wires made by combined in situ/ex situ process

Cited by 37 publications

References 9 publications

MgB2 coated superconducting tapes with high critical current densities fabricated by hybrid physical–chemical vapor deposition

MgB2 coated superconducting tapes with high critical current densities fabricated by hybrid physical–chemical vapor deposition

Formation of AlCuFe icosahedral quasicrystal by mechanical alloying: XAFS and XRD studies

Superconducting properties of nanocrystalline MgB2

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Product

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Superconducting properties of nanocrystalline MgB₂