Enhanced critical current density in undoped MgB2 prepared by in situ/ex situ combination technique

Shah, M. Shahabuddin; Shahabuddin, Mohammed; Parakkandy, Jafar M.; Qaid, Salem A. S.; Alzayed, Nasser S.

doi:10.1016/j.ssc.2015.06.004

Cited by 10 publications

(2 citation statements)

References 19 publications

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“…Considering the microstructure of these MgB 2 bulk samples in the SEM diagrams, we can find that the PaF exhibit obvious discrepancy in the microstructural defects and the slight discrepancy in the crystallite size. It is well known that the smaller crystallite size signifies an increase in the number of the MgB 2 grains and the grain boundary per unit volume, which can enhance the number of effective pinning centers and further improve the superconducting properties of samples [31]. This principle can be well verified from the correspondence between the J c,PeF (figure 3) and the average crystallite size of the PeF in this study, which indicates that the J c is greatly influenced by the crystallite size for the PeF of the SPSed MgB 2 bulk samples.…”

Section: Resultsmentioning

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: Resultsmentioning

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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“…It is easy to see that S1-PeF has the smallest average size (0.24 µm), and S2-PaF has the largest average size (0.29 µm). A smaller crystal size means more MgB 2 particles and grain boundaries per unit volume, which can increase the number of effective pinning centers and further improve the J C of MgB 2 [ 32 ]. This is consistent with the trend of J C in Figure 3 and Figure 4 , which confirms that the J C is greatly influenced by the crystal size of the SPSed MgB 2 bulks.…”

Section: Resultsmentioning

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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The influence of Mn nanoparticles on superconducting properties and pinning mechanism of MgB2

Durmuş

Kocabaş

2022

J Mater Sci: Mater Electron

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Enhanced critical current density in undoped MgB2 prepared by in situ/ex situ combination technique

Cited by 10 publications

References 19 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

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

The influence of Mn nanoparticles on superconducting properties and pinning mechanism of MgB2

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Enhanced critical current density in undoped MgB2 prepared by in situ/ex situ combination technique

Cited by 10 publications

References 19 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

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

The influence of Mn nanoparticles on superconducting properties and pinning mechanism of MgB2

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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