Spark plasma sintering of bulk MgB<sub>2</sub> and levitation force measurements

Noudem, Jacques; Bernstein, P.; Dupont, Louis; Martin, Florencio; Sotelo, Guilherme Gonçalves; Dias, D. H. N.; Andrade, R. de; Muralidhar, M.; Murakami, Masato

doi:10.1088/1361-6668/ab5f3e

Cited by 17 publications

(4 citation statements)

References 23 publications

(25 reference statements)

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“…However, samples prepared by conventional sintering methods cannot show outstanding performance because of the low density, the presence of impurity, etc. To solve these problems, many improved preparation methods are used to fabricate high-performance MgB 2 superconductors with high purity and large size, such as hot pressing sintering, hot isostatic pressing and spark plasma sintering (SPS) [5][6][7][8][9]. In this study, we fabricated MgB 2 bulk samples by the SPS technique, which combines the pulsed current and the uniaxial pressure.…”

Section: Introductionmentioning

confidence: 99%

The discrepancies in different facets of MgB₂ bulk superconductors prepared under various sintering durations by spark plasma sintering

Zhang

Lou

et al. 2021

Supercond. Sci. Technol.

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Seven MgB2 bulk superconductors with good superconductivity and crystallinity were prepared under the pressure of 50 MPa at 950 °C and different sintering durations (15 ∼ 240 min) by spark plasma sintering (SPS), with the onset critical temperature (T c,onset) around 37.5 K. The superconducting properties and microstructure measured from the facets perpendicular (PeF) and parallel (PaF) to the compression direction of the SPSed MgB2 bulk samples were also analyzed to investigate the effect of the sintering duration on the MgB2 bulks and the discrepancy between the PeF and the PaF. The optimum performance was obtained from the sample prepared for 45 min for both facets, and the critical current density (J c) measured from the PeF and the PaF are 364 kA cm−2 and 344 kA cm−2 in self field at 20 K, respectively. The PeF exhibits better Jc performance than the PaF at low fields and the PaF exhibits better J c performance than the PeF at high fields. It can be concluded that the sintering duration affects the properties of the PeF mainly by changing their crystallite size. While for the PaF, the sintering duration mainly affects the microstructural defects, such as cracks, pores and secondary phase particles, thus further affecting their J c performances. In terms of the flux pinning mechanism of the SPSed MgB2 bulk samples, the PaF is less susceptible to sintering duration than the PeF, and the better J c performance of the PaF at high fields is due to the stronger grain boundary pinning. It can be also found that the point pinning being stronger at higher temperature is the result of the decreasing anisotropy of MgB2 bulk samples with the temperature.

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Section: Introductionmentioning

confidence: 99%

The discrepancies in different facets of MgB₂ bulk superconductors prepared under various sintering durations by spark plasma sintering

Zhang

Lou

et al. 2021

Supercond. Sci. Technol.

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“…While 'ex-situ' methods yield materials with dense cores and a high homogeneity, they suffer from weak granular conductivity and low critical current density. To enhance the critical current density, various approaches have been investigated, including reducing grain size and Reproduced from [78]. © IOP Publishing Ltd. All rights reserved.…”

Section: Production Techniques Of Mgbmentioning

confidence: 99%

“…Figure 7. Magnetic levitation force measurement (closed symbol) and magnetic moment curve (open symbol) were carried out on MgB 2 samples fabricated under the same conditions [78].Reproduced from[78]. © IOP Publishing Ltd. All rights reserved.…”

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Review on high-performance bulk MgB₂ superconductors

Muralidhar,

Shadab,

Sai Srikanth

et al. 2023

J. Phys. D: Appl. Phys.

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Although the fascinating effect of superconductivity was discovered more than one hundred years ago, only a few low-temperature superconductors, especially Nb3Sn and NbTi, have reached everyday-life use. After the discovery of superconductivity in MgB2 in 2001, a boom appeared in interest in employing MgB2 in commercial applications, facilitated by simple crystallographic structure, high critical temperature, low-cost raw ingredients, simple and fast production, and other advantages for moderate temperature applications. It only lacks high flux pinning and good mechanical performance. In this review, the implications of manufacturing procedures on the superconducting properties, crystal and electronic structure of MgB2 are discussed. The advantages and drawbacks of various manufacturing processes will be presented, as well as the ways how to improve MgB2 superconducting performance. The impact of oxygen reduction, elements doping, the introduction of defects and additives, and the effect of precursor refinement on superconducting properties are here compiled to give an overview of the progress of flux pinning enhancement in bulk MgB2.

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“…It is known that MgB 2 is an anisotropic material [ 24 , 25 ], which means its properties may be different in different directions. The SPS process is carried out under uniaxial pressure, so there are perpendicular (PeF) and parallel (PaF) facets to the compression direction of the uniaxial pressure.…”

Section: Introductionmentioning

confidence: 99%

The Influence of Preparation Temperature on the Different Facets of Bulk MgB2 Superconductors

Zhang

et al. 2023

Micromachines

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Two MgB2 samples were prepared using the spark plasma sintering (SPS) technique at different temperatures—950 °C (S1) and 975 °C (S2)—for 2 h under 50 MPa pressure to study the influence of preparation temperature on different facets, namely those perpendicular (PeF) and parallel (PaF) to the compression direction of uniaxial pressure during the SPS of MgB2 samples. We analyzed the superconducting properties of the PeF and PaF of two MgB2 samples prepared at different temperatures from the curves of the critical temperature (TC), the curves of critical current density (JC), the microstructures of MgB2 samples, and the crystal size from SEM. The values of the onset of the critical transition temperature, Tc,onset, were around 37.5 K and the transition widths were about 1 K, which indicates that the two samples exhibit good crystallinity and homogeneity. The PeF of the SPSed samples exhibited slightly higher JC compared with that of the PaF of the SPSed samples over the whole magnetic field. The values of the pinning force related to parameters h0 and Kn of the PeF were lower than those of the PaF, except for Kn of the PeF of S1, which means that the PeF has a stronger GBP than the PaF. In low field, the most outstanding performance was S1-PeF, whose critical current density (JC) was 503 kA/cm2 self-field at 10 K, and its crystal size was the smallest (0.24 µm) among all the tested samples, which is consistent with the theory that a smaller crystal size can improve the JC of MgB2. However, in high field, S2-PeF had the highest JC value, which is related to the pinning mechanism and can be explained by grain boundary pinning (GBP). With an increase in preparation temperature, S2 showed a slightly stronger anisotropy of properties. In addition, with an increase in temperature, point pinning becomes stronger to form effective pinning centers, leading to a higher JC.

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Spark plasma sintering of bulk MgB₂ and levitation force measurements

Abstract: We present preliminary results suggesting that MgB 2 is a superconductor that could be used in Maglev vehicles. For this purpose, we compare the levitation capability of MgB 2 samples to those of YBCO bulks.

Cited by 17 publications

References 23 publications

The discrepancies in different facets of MgB₂ bulk superconductors prepared under various sintering durations by spark plasma sintering

The discrepancies in different facets of MgB₂ bulk superconductors prepared under various sintering durations by spark plasma sintering

Review on high-performance bulk MgB₂ superconductors

The Influence of Preparation Temperature on the Different Facets of Bulk MgB2 Superconductors

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Spark plasma sintering of bulk MgB2 and levitation force measurements

Abstract: We present preliminary results suggesting that MgB 2 is a superconductor that could be used in Maglev vehicles. For this purpose, we compare the levitation capability of MgB 2 samples to those of YBCO bulks.

Cited by 17 publications

References 23 publications

The discrepancies in different facets of MgB2 bulk superconductors prepared under various sintering durations by spark plasma sintering

The discrepancies in different facets of MgB2 bulk superconductors prepared under various sintering durations by spark plasma sintering

Review on high-performance bulk MgB2 superconductors

The Influence of Preparation Temperature on the Different Facets of Bulk MgB2 Superconductors

Contact Info

Product

Resources

About

Spark plasma sintering of bulk MgB₂ and levitation force measurements

The discrepancies in different facets of MgB₂ bulk superconductors prepared under various sintering durations by spark plasma sintering

The discrepancies in different facets of MgB₂ bulk superconductors prepared under various sintering durations by spark plasma sintering

Review on high-performance bulk MgB₂ superconductors