Spark Plasma Synthesis and Sintering of Superconducting MgB&lt;sub&gt;2&lt;/sub&gt;-Based Materials

Prikhna, T. A.; Noudem, Jacques; Gawalek, W.; Mamalis, A.G.; Солдатов, А. В.; Savchuk, Yaroslav; Moshchil, Viktor; Eisterer, M.; Weber, H.W.; Дуб, С. Н.; Habisreuther, T.; Dellith, Jan; You, Shujie; Schmidt, Christa; Karau, F.; Dittrich, Ulrich; Vajda, István; Sergienko, Nina; Litzkendorf, D.; Chaud, X.; Sverdun, V. B.; Kuznietsov, Roman

doi:10.4028/www.scientific.net/msf.721.3

Cited by 10 publications

(15 citation statements)

References 9 publications

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“…The decomposition was observed to intensify when the sintering temperature was increased above 850 °C. However, compared to the reported literature [ 31 ], the effect of the low proportions of the formed secondary phase was seen in the improvement of the flux pinning characteristics due to the refinement of the grains, which was articulated later in the sample microstructure.…”

Section: Resultsmentioning

confidence: 61%

Synthesis of Dense MgB2 Superconductor via In Situ and Ex Situ Spark Plasma Sintering Method

et al. 2021

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In this study, high-density magnesium diboride (MgB2) bulk superconductors were synthesized by spark plasma sintering (SPS) under pressure to improve the field dependence of the critical current density (Jc-B) in MgB2 bulk superconductors. We investigated the relationship between sintering conditions (temperature and time) and Jc-B using two methods, ex situ (sintering MgB2 synthesized powder) and in situ (reaction sintering of Mg and B powder), respectively. As a result, we found that higher density with suppressed particle growth and suppression of the formation of coarse particles of MgB4 and MgO were found to be effective in improving the Jc-B characteristics. In the ex situ method, the degradation of MgB2 due to pyrolysis was more severe at temperatures higher than 850 °C. The sample that underwent SPS treatment for a short time at 850 °C showed higher density and less impurity phase in the bulk, which improved the Jc-B properties. In addition, the in situ method showed very minimal impurity with a corresponding improvement in density and Jc-B characteristics for the sample optimized at 750 °C. Microstructural characterization and flux pinning (fP) analysis revealed the possibility of refined MgO inclusions and MgB4 phase as new pinning centers, which greatly contributed to the Jc-B properties. The contributions of the sintering conditions on fP for both synthesis methods were analyzed.

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Section: Resultsmentioning

confidence: 61%

Synthesis of Dense MgB2 Superconductor via In Situ and Ex Situ Spark Plasma Sintering Method

et al. 2021

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“…The samples were prepared at 600, 800, and 1050 • C under 0.1 MPa pressure in Ar (pressureless synthesis, PL), elevated pressure of 30 MPa (hot pressing, HotP) in contact with hexagonal BN and spark plasma sintering (50 MPa, SPS) [5] in contact with graphite and high quasi-hydrostatic (2 GPa, HP) [9] See http://www.ieee.org/publications_standards/publications/rights/index.html for more information. of the materials were characterized by X-ray diffraction with Rietveld refinement and SEM with microprobe X-ray and Auger spectroscope (JAMP-9500F).…”

Section: Methodsmentioning

confidence: 99%

“…Eisterer [5]. The discussed MgB 2 -based materials demonstrate a high superconducting performance and an enhanced connectivity between the superconducting grains [6] which is much higher than that reported elsewhere (usually less than 50%) [7].…”

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confidence: 91%

Effect of Nanostructural Inhomogeneities on the Superconducting Characteristics of <inline-formula> <tex-math notation="TeX">$\hbox{MgB}_{2}$</tex-math></inline-formula> With Enhanced Grain Connectivity

Prikhna

Eisterer

Goldacker

et al. 2015

IEEE Trans. Appl. Supercond.

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MgB 2 -based bulk materials synthesized under 30 MPa-2 GPa pressure demonstrated an enhanced connectivity A F ∼ 50%−98%, as compared to most other reports (below 50%), and a shielding fraction of 75%-100%. The materials inhibit high critical current densities j c , but no strict correlation was found between A F and j c . On the other side, we found correlations between j c and the distribution of nanostructural inhomogeneities such as impurity oxygen in the form of oxygen-enriched Mg-B-O nanolayers or nanoinclusions and its solution in the MgB 2 matrix and as well with the amount and size of higher magnesium borides MgB x , x ≥ 4 inclusions. The distribution of boron-and oxygenenriched (as compared to stoichiometric MgB 2 ) inhomogeneities affects the type of pinning and, thus, j c , and to some extent, it can be regulated by synthesis temperatures and pressures and by Ti addition. Auger spectroscopy, scanning electron microscopy, and X-ray with Rietveld refinement were used for structural study.

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“…The lower temperatures of these processes make it difficult to sinter MgB2 at temperatures near the melting point, necessitating the use of additional methods such as hot pressing [29,30], hot isostatic pressing [31,32], and spark plasma sintering [33][34][35] to achieve dense and well-connected grain boundaries in ex-situ MgB2 bulks and wires.…”

Section: Introductionmentioning

confidence: 99%

Microstructural connectivity in sintered ex-situ MgB2 bulk superconductors

Shimada

Hata

Ikeda

et al. 2016

Journal of Alloys and Compounds

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We have performed combined high-resolution microstructural and grain orientation analyses to understand the key microstructural factors associated with high intergranular transport current in polycrystalline bulk forms of MgB2. The ex-situ method can produce MgB2 with relatively high packing factors; nevertheless, the connectivity of MgB2 fabricated by the ex-situ method (ex-situ MgB2) was less than that of in-situ MgB2. The poor connections between MgB2 grain aggregates cause the low connectivity of ex-situ MgB2. Plate-like pores are present between the aggregates of MgB2 grains in ex-situ MgB2; these pores remain even after prolonged self-sintering at high temperatures. In addition, MgB2 crystals decompose to MgB4 in sintering for a long period. Moreover, MgO particles are formed between MgB2 grain aggregates and inhibit interaggregate connections. In contrast, in-situ MgB2 fabricated at the same sintering conditions exhibits spherical pores between MgB2 grains, resulting in a uniform pore distribution and intergranular connection. These problems must be addressed to further enhance the connectivity in ex-situ MgB2.

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Spark Plasma Synthesis and Sintering of Superconducting MgB<sub>2</sub>-Based Materials

Cited by 10 publications

References 9 publications

Synthesis of Dense MgB2 Superconductor via In Situ and Ex Situ Spark Plasma Sintering Method

Synthesis of Dense MgB2 Superconductor via In Situ and Ex Situ Spark Plasma Sintering Method

Effect of Nanostructural Inhomogeneities on the Superconducting Characteristics of <inline-formula> <tex-math notation="TeX">$\hbox{MgB}_{2}$</tex-math></inline-formula> With Enhanced Grain Connectivity

Microstructural connectivity in sintered ex-situ MgB2 bulk superconductors

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