The reactive liquid Mg infiltration process to produce large superconducting bulk MgB2 manufacts

Giunchi, G.; Ripamonti, G.; Cavallin, T.; Bassani, E.

doi:10.1016/j.cryogenics.2005.11.011

Cited by 107 publications

(75 citation statements)

References 11 publications

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“…Detailed analysis suggests that material has about 5% MgO and13% Mg. MgO has likely formed as a result of reaction between excess Mg and O during milling process that was used to powder the bulk. Giunchi et al reported the presence of boron rich phases such as Mg 2 B 25, MgB 4 or MgB 7 in the reactive liquid infiltration process [31,33], although no such phases were detected in the samples prepared in this study. This may be explained by the Mg-rich atmosphere generated intrinsically as part of the fabrication process, which facilitates the formation of Mg-rich borides in the MgB x family, and MgB 2 in particular.…”

Section: Methodsmentioning

confidence: 54%

“…Improved versions of this process were reported subsequently by Giunchi et al [30] for the fabrication of bulk MgB 2 artefacts, in which Mg bulk and B powder are placed in a metallic container. The container was then welded closed and heat-treated at 950 ºC to obtain dense, bulk MgB 2 , with the initial arrangement of B and Mg bulk in the container being used to define the geometry of the final product [31].…”

Section: Introductionmentioning

confidence: 99%

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Synthesis of dense bulk MgB₂by an infiltration and growth process

Bhagurkar

Yamamoto

Babu

et al. 2014

Supercond. Sci. Technol.

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Abstract:We report the processing of dense, superconducting MgB 2 (ρ ≈ 2.4 g/cm 3 )by an infiltration and growth technique. The process, which involves infiltration of liquid magnesium at 750 ºC into a pre-defined boron precursor pellet, is relatively simple, results in the formation of a hard, dense structure and has the potential to fabricate large bulk samples of complex geometries. X-ray diffraction has been used to confirm the presence of the MgB 2 primary phase with only residual magnesium content in the fully processed samples. The samples exhibit sharp superconducting transitions at 38.4 K and have critical current densities of up to 260 kA/cm 2 in selffield at 5 K. Modest measured values of Hc 2 (0) of 17 T suggest that superconductivity in bulk MgB 2 fabricated by this technique is in the clean pairing limit.

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Section: Methodsmentioning

confidence: 54%

Section: Introductionmentioning

confidence: 99%

Synthesis of dense bulk MgB₂by an infiltration and growth process

Bhagurkar

Yamamoto

Babu

et al. 2014

Supercond. Sci. Technol.

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“…Each manufacture requires a careful design of the container and a careful distribution of the reactants. The presence of small islands of Mg 2 B 25 can cause a local reduction of the superconducting current density [8]. If the application needs temperatures higher than 77 K, high-temperature superconductors (HTSs) must be used.…”

Section: Introductionmentioning

confidence: 99%

“…If temperatures lower than 40 K are allowed by the application, magnesium diboride (MgB 2 ) can be used to make efficient magnetic shields [6]. The reactive liquid infiltration method allows one to realize superconducting tubes with lengths of several tens of centimetres [8,9]. This method consists in a liquid infiltration of magnesium inside preforms of boron powders, in a closed metallic container that is heated at around 900 °C for one half to several hours.…”

Section: Introductionmentioning

confidence: 99%

Field penetration into hard type-II superconducting tubes: effects of a cap, a non-superconducting joint, and non-uniform superconducting properties

Denis

Dirickx

Vanderbemden

et al. 2007

Supercond. Sci. Technol.

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Using the numerical method of Brandt (1998 Phys. Rev. B 58 6506), we study the penetration of a uniform magnetic field that is gradually applied parallel to the axis of finite type-II superconducting tubular samples with strong pinning. This study is carried out in view of designing low-frequency magnetic shields by exploiting the diamagnetic properties of type-II superconductors. First, we compare the field penetration into open and closed tubes. For long tubes (length larger than three times the outer diameter), we show that a cap weakly affects the maximum magnetic induction that can be shielded, but greatly increases the region over which the field is nearly uniform. When the length of the tube is shorter, both the maximum shieldable magnetic induction and the uniformity of the field attenuation are enhanced by closing the tube. We also show that making a hole in the cap, which is often necessary for applications, does not greatly affect the shielding properties provided the diameter of the hole is small compared to that of the tube (hole diameter smaller than a quarter of the outer tube diameter). In view of designing large size magnetic shields, superconducting tubes of finite size need to be joined together. We therefore examine in a second part how the presence of a non-superconducting joint between the tubes affects the shielding efficiency. It is shown that the effect of a joint depends upon its position along the tube axis and strongly increases with its size. Third, we study how non-uniform superconducting properties affect the shielding capabilities.

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“…The reaction between liquid Mg and B powder produces a more stable material, with respect to the hot pressing technique, at temperatures of a few hundred K above the Mg melting point and at moderate pressure. This procedure allows one to obtain specimens of high density and dimensions of the order of tens on centimeters, showing very high mechanical strength [19,20].…”

Section: The Superconducting Mgb 2 Cavitymentioning

confidence: 99%

Microwave response of a cylindrical cavity made of bulk MgB2 superconductor

Gallitto

Bonsignore

Vigni

et al. 2008

Physica C: Superconductivity and its Applications

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We report on the microwave properties of a resonant cylindrical cavity made of bulk MgB 2 superconductor, produced by the reactive liquid Mg infiltration process. The frequency response of the cavity has been measured in the range 5 ÷ 13 GHz. Among the various modes, the TE 011 , resonating at 9.79 GHz, exhibits the highest quality factor. For this mode, we have determined the temperature dependence of the quality factor, obtaining values of the order of 10 5 in the temperature range 4.2 ÷ 30 K. The values of the surface resistance deduced from the measurements of the quality factor agree quite well with those independently measured in a small sample of MgB 2 extracted from the same specimen from which the cavity has been obtained.

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The reactive liquid Mg infiltration process to produce large superconducting bulk MgB2 manufacts

Cited by 107 publications

References 11 publications

Synthesis of dense bulk MgB₂by an infiltration and growth process

Synthesis of dense bulk MgB₂by an infiltration and growth process

Field penetration into hard type-II superconducting tubes: effects of a cap, a non-superconducting joint, and non-uniform superconducting properties

Microwave response of a cylindrical cavity made of bulk MgB2 superconductor

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The reactive liquid Mg infiltration process to produce large superconducting bulk MgB2 manufacts

Cited by 107 publications

References 11 publications

Synthesis of dense bulk MgB2by an infiltration and growth process

Synthesis of dense bulk MgB2by an infiltration and growth process

Field penetration into hard type-II superconducting tubes: effects of a cap, a non-superconducting joint, and non-uniform superconducting properties

Microwave response of a cylindrical cavity made of bulk MgB2 superconductor

Contact Info

Product

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Synthesis of dense bulk MgB₂by an infiltration and growth process

Synthesis of dense bulk MgB₂by an infiltration and growth process