Flux pinning mechanism in SiC and nano-C doped MgB2: evidence for transformation fromδTctoδℓpinning

Ghorbani, Shaban Reza; Farshidnia, G; Wang, Xiaolin; Dou, Shi Xue

doi:10.1088/0953-2048/27/12/125003

Cited by 14 publications

(9 citation statements)

References 30 publications

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“…However, the pinning behavior at h > 0.5 for u-MgB 2 and n-MgB 2 have shifted towards right indicating the high-field pinning showing the signs of flux pinning from carbon-substitution. These results are in accordance with some previous reports [39]. Optimization of bulk MgB 2 material with dipping in synthetic motor oil before sintering in long duration would further improve the performance of material, which would be considered to be the next task, as it would serve to be useful for day to life applications.…”

Section: Resultssupporting

confidence: 92%

Enhanced Flux Pinning Performance of Bulk MgB2 via Immersion of Synthetic Motor Oil

Santosh

Arvapalli

Muralidhar

2022

J Supercond Nov Magn

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The present investigation focuses on the incorporation of synthetic motor oil as an inexpensive, rich carbon source in bulk MgB2 superconductor and its effect on superconducting and flux pinning properties. A set of three MgB2 bulk samples were prepared from commercial high-purity powders of Mg metal and amorphous B powder utilizing a conventional in situ solid-state reaction process. Before sintering, the MgB2 samples were immersed in used and new synthetic motor oil for a standby time of 30 min and sintered in pure Ar atmosphere at 775 °C for 3 h. X-ray powder diffractometer (XRD) analysis confirmed that single-phase formation of MgB2 with a small shift in X-ray diffraction peaks especially at (110) towards the peak position due to the effect of carbon substitution into the boron sites in lattice for samples immersed in new and used synthetic oil. The magnetization measurements indicated the Tc (onset) value to somewhat decrease to 37.5 K as a result of carbon doping. Microstructural observations with scanning electron microscopy (SEM) suggested that fine nano-sized MgB2 grains improved self-field critical current density around 3.8 × 105 A/cm2 at 20 K for all samples studied. Further, the high-field critical current density (Jc) was improved especially for the sample immersed in used synthetic motor oil with the value of 2.7 × 104 A/cm2, 6 × 103 A/cm2 at 20 K, and at 3 T and 4 T, which is higher as compared to pure-MgB2 sample. In essence, the results signify that the bulk MgB2 samples immersed with used synthetic motor oil would improve the bulk performance at high magnetic fields indicating to be a viable option for industrial applications.

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Section: Resultssupporting

confidence: 92%

Enhanced Flux Pinning Performance of Bulk MgB2 via Immersion of Synthetic Motor Oil

Santosh

Arvapalli

Muralidhar

2022

J Supercond Nov Magn

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“…In comparison, when we tried to incorporate carbon using carbon-encapsulated boron, we observed a change to 3.078 Å for just 1.5 wt% addition [14]. In case of 5 % nano-C doping, the value was reported to drop to 3.060 Å [25]. Similarly, the lattice parameter 'c' also didn't change.…”

Section: Resultsmentioning

confidence: 90%

Effect of boron precursor ultra-sonicated in hexane medium on the critical current density of sintered bulk MgB₂

Arvapalli

Jirsa

Murakami

et al. 2022

J. Phys.: Conf. Ser.

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The large coherence length of MgB2 material allows large defects such as grain boundaries to act as strong pinning centres. As an alternative to the high-cost commercial nano precursors, we used a novel ultra-sonication technique to refine a cheap rough boron precursor and avoid the use of the expensive commercial nano amorphous boron powder. Recent novel low-cost ultra-sonication technique proved to improve the critical current density, J c, of MgB2. Here, we discuss the consequences of ultra-sonication duration in hexane medium on the boron precursor as well as the superconducting properties of MgB2 bulks. XRD revealed small peaks corresponding to unreacted Mg. First derivative of susceptibility was plotted as a function of temperature to explain the Tc,onset and ΔTc. J c was found to grow if the MgB2 bulk was prepared of boron ultra-sonicated for up to 30 minutes and then reduced with further boron ultra-sonication (60 minutes). SEM micrographs showed that boron powder subjected to longer ultra-sonication resulted in agglomeration of broken boron particles, forming large MgB2 grains. Based on the comparison of superconducting properties with previous results, we speculate that viscosity of the ultra-sonication medium might have a crucial role in the refinement of boron precursor powder.

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“…It is noteworthy that the δ l pinning contribution to J c is more effective than the δ T c pinning contribution, as nonsuperconducting phase defects provide much stronger pinning to vortices. For example, in the MgB 2 superconductor, the addition of nonsuperconducting SiC doping significantly improved J c while completely transforming the pinning mechanism from δ T c pinning to δ l pinning . Additionally, in YBCO films with higher J c , only δ l pinning type provides pinning contribution .…”

Section: Resultsmentioning

confidence: 99%

“…For example, in the MgB 2 superconductor, the addition of nonsuperconducting SiC doping significantly improved J c while completely transforming the pinning mechanism from δT c pinning to δl pinning. 61 Additionally, in YBCO films with higher J c , only δl pinning type provides pinning contribution. 57 Therefore, the δl pinning is responsible for higher J c in thinner FST CCs, while the thickness effect is caused by the weakening role of the δl pinning and the strengthening role of the δT c pinning.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

Critical Role Played by Interface Engineering in Weakening Thickness Dependence of Superconducting and Structural Properties of FeSe_0.5Te_0.5-Coated Conductors

Song

Xiong³

et al. 2023

ACS Appl. Mater. Interfaces

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Increasing the thickness of a superconducting layer and simultaneously reducing the thickness effect in iron-based superconducting coated conductors are particularly essential for improving the critical current I c . Here, for the first time, we have deposited high-performance FeSe 0.5 Te 0.5 (FST) superconducting films up to 2 μm on LaMnO 3 -buffered metal tapes by pulsed laser deposition. An interface engineering strategy, alternating growth of a 10 nm-thick nonsuperconducting FST seed layer and a 400 nmthick FST superconducting layer, was employed to guarantee the crystalline quality of the films with thicknesses of the order of micrometers, resulting in a highly biaxial texture with grain boundary misorientation angle less than the critical value θ c ∼ 9°. Moreover, the thickness effect, that the critical current density (J c ) shows a clear dependence on thickness as in cuprates, is reduced by the interface engineering. Also, the maximum J c was found for a 400 nm-thick film with 1.3 MA/cm 2 in self-field at 4.2 K and 0.71 MA/cm 2 (H∥ab) and 0.50 MA/cm 2 (H∥c) at 9 T. Anisotropic Ginzburg−Landau scaling indicates that the major pinning centers vary from correlated to uncorrelated as the film thickness increases, while the thickness effect is most likely related to the weakening of flux pinning by the fluctuation of charge-carrier mean free path (δl) and strengthening of flux pinning caused by the variation of superconducting transition temperature (δT c ) due to offstoichiometry with thickness.

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Flux pinning mechanism in SiC and nano-C doped MgB₂: evidence for transformation fromδT_ctoδℓpinning

Cited by 14 publications

References 30 publications

Enhanced Flux Pinning Performance of Bulk MgB2 via Immersion of Synthetic Motor Oil

Enhanced Flux Pinning Performance of Bulk MgB2 via Immersion of Synthetic Motor Oil

Effect of boron precursor ultra-sonicated in hexane medium on the critical current density of sintered bulk MgB₂

Critical Role Played by Interface Engineering in Weakening Thickness Dependence of Superconducting and Structural Properties of FeSe_0.5Te_0.5-Coated Conductors

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Flux pinning mechanism in SiC and nano-C doped MgB2: evidence for transformation fromδTctoδℓpinning

Cited by 14 publications

References 30 publications

Enhanced Flux Pinning Performance of Bulk MgB2 via Immersion of Synthetic Motor Oil

Enhanced Flux Pinning Performance of Bulk MgB2 via Immersion of Synthetic Motor Oil

Effect of boron precursor ultra-sonicated in hexane medium on the critical current density of sintered bulk MgB2

Critical Role Played by Interface Engineering in Weakening Thickness Dependence of Superconducting and Structural Properties of FeSe0.5Te0.5-Coated Conductors

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Product

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Flux pinning mechanism in SiC and nano-C doped MgB₂: evidence for transformation fromδT_ctoδℓpinning

Effect of boron precursor ultra-sonicated in hexane medium on the critical current density of sintered bulk MgB₂

Critical Role Played by Interface Engineering in Weakening Thickness Dependence of Superconducting and Structural Properties of FeSe_0.5Te_0.5-Coated Conductors