GLAG theory for superconducting property variations with A15 composition in Nb3Sn wires

Li, Yingxu; Gao, Yuanwen

doi:10.1038/s41598-017-01292-4

Cited by 16 publications

(24 citation statements)

References 35 publications

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“…The penetration depth λ(0) = X s (H = 0, T → 0)/µ 0 ω ∼ 100 nm is evaluated by extrapolating X s (µ 0 H = 0 T) at low temperature. The obtained value is in fair agreement with reported data [24].…”

Section: Resultssupporting

confidence: 93%

Surface Impedance Measurements on Nb<inline-formula> <tex-math notation="LaTeX">$_{3}$</tex-math> </inline-formula>Sn in High Magnetic Fields

Alimenti

Pompeo

Torokhtii

et al. 2019

IEEE Trans. Appl. Supercond.

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Nb 3 Sn is a superconductor of great relevance for perspective RF applications. We present for the first time surface impedance (Zs) measurements at 15 GHz and low RF field amplitude on Nb 3 Sn in high magnetic fields up to 12 T, with the aim of increasing the knowledge of Nb 3 Sn behavior in such conditions. Zs is a fundamental material parameter that directly gives useful information about the dissipative and reactive phenomena when the superconductor is subjected to high-frequency excitations. Therefore, we present an analysis of the measured Zs with the aim of extracting interesting data about pinning in Nb 3 Sn at high frequencies. From Zs we extract the vortex motion complex resistivity to obtain the r-parameter and the depinning frequency νp in high magnetic fields. The comparison of the results with the literature shows that the measured νp on bulk Nb 3 Sn is several times greater than that of pure Nb. This demonstrates how Nb 3 Sn can be a good candidate for RF technological applications, also in high magnetic fields.Index Terms-High magnetic fields, microwave, Nb 3 Sn, depinning frequency, surface impedance.

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Section: Resultssupporting

confidence: 93%

Surface Impedance Measurements on Nb<inline-formula> <tex-math notation="LaTeX">$_{3}$</tex-math> </inline-formula>Sn in High Magnetic Fields

Alimenti

Pompeo

Torokhtii

et al. 2019

IEEE Trans. Appl. Supercond.

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“…Therefore, more information is required to fully understand the properties of the foam samples as well as of the IG-processed YBCO bulks. Recently, Kramer plots were empolyed to describe the flux pinning properties in Nb 3 Sn [19], [21] and YBCO thin films [20]. In the latter case, the Kramer model including thermal activation was applied.…”

Section: Resultsmentioning

confidence: 99%

“…[20], the Kramer model was extended to include thermal activation effects, which could describe then successfully the shape of the curves in the Kramer plots. Remarkably, another recent paper [21] could describe the superconducting property variations in Nb 3 Sn using the GLAG theory, and they could calculate the respective variations of the pinning force scaling and the Kramer plots. This approach could be an interesting step forward also to understand the influence of the changes of the superconducting properties with position in the high-T c superconductors.…”

Section: Resultsmentioning

confidence: 99%

“…As the all foam samples investigated here were found to exhibit a welldeveloped scaling behavior, but the shape of the pinning curves is entirely different from other high-T c superconductors (see, e.g., [15]- [17]), we perform further discussion on the flux pinning properties of the foam struts using Kramer plots [18] following the approach of Oh et al [19], [20]. The advantage of the Kramer plots to discuss the flux pinning properties is the fact that there are no uncertainities like the determination of the irreversibility fields involved [21].…”

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confidence: 99%

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Current Flow and Flux Pinning Properties of YBCO Foam Struts

Koblischka

Koblischka-Veneva

Berger

et al. 2019

IEEE Trans. Appl. Supercond.

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The current flow and the flux pinning properties on struts of superconducting YBa2Cu3Ox (YBCO) foams are analyzed in detail in the temperature range 60 K ≤ T ≤ Tc. For this purpose, magnetization loops were measured on foam struts taken from various positions of a 5 × 2 × 2 cm 3 large foam sample prepared at RWTH Aachen. From these data, the critical current densities, jc, and the flux pinning forces, Fp = jc × B, were calculated and pinning force scaling diagrams Fp/Fp,max vs. h = Ha/Hirr were established. The scaling in the temperature range 60 K < T < 90 K was found to be well developed for all samples with peak positions, h0, above 0.4, which is an indication of δTc-pinning. The shape of the pinning functions is found to be completely different from all other high-Tc materials and varies only slightly with position. This specific dome-shape cannot be described by an addition of several pinning functions, and the parameters p and q do not fit to the description of Dew-Hughes. Therefore, we employ Kramer plots to obtain more information on the flux pinning mechanism. Index Terms-Foam, YBCO, critical currents, flux pinning, scaling. I. INTRODUCTION S UPERCONDUCTING foams are an interesting class of high-T c materials for various applications due to several advantages as compared to conventional bulk samples [1]-[5]. These advantages include facile oxygenation and effective cooling processes, scalability, light weight of the samples, easy shaping and reduced material costs [6], [7]. The superconducting foams may be useful for a variety of applications, starting from fault-current limiters to trapped field magnets and elements in electric motors and generators, where the reduced weight may play an important role. However, the high-T c superconducting foam samples prepared up to now pose many new questions concerning the current flow in such a 3D material and the corresponding flux pinning properties, which are essential to be answered for future applications of these materials. One important issue is the detailed understanding of Manuscript received xx.xx.xxxx. This work is a part of the SUPERFOAM international project funded by ANR and DFG under the references ANR-17-CE05-0030 and DFG-ANR Ko2323-10.

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“…Strong gradients of tin composition at grain boundaries can reduce the critical current density, the flux pinning force and flux pinning scaling field in superconducting wires [29][30][31]. Additionally, highly degraded quality factors have been observed in SRF cavities with prominent tin segregation at grain boundaries [28].…”

Section: Introductionmentioning

confidence: 99%

$\textit{Ab Initio}$ Theory of the Impact from Grain Boundaries and Substitutional Defects on Superconducting Nb$_3$Sn

Kelley,

Sitaraman,

Arias

2020

Preprint

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Grain boundaries play a critical role in applications of superconducting Nb3Sn: in dc applications, grain boundaries preserve the material's intrinsically high critical-current by pinning flux, while in ac applications grain boundaries can provide weak points for flux entry and lead to significant dissipation. We present the first ab initio study to investigate the physics of different boundary types in Nb3Sn using density functional theory. We identify an energetically favorable selection of tilt and twist grain boundaries of distinct orientations. We find that clean grain boundaries free of point defects reduce the Fermi-level density of states by a factor of two, an effect that decays back to the bulk electronic structure ∼1-1.5 nm from the boundary. We further calculate the binding free-energies of tin substitutional defects to multiple boundaries, finding a strong electronic interaction that extends to a distance comparable to that of the reduction of density of states. Associated with this interaction, we discover a universal trend in defect electronic entropies near a boundary. We probe the effects of defect segregation on grain boundary electronic structure and calculate the impact of substitutional impurities on the Fermi-level density of states in the vicinity of a grain boundary, finding that titanium and tantalum have little impact regardless of placement, whereas tin, copper, and niobium defects each have a significant impact but only on sites away from the boundary core. Finally, we consider how all of these effects impact the local superconducting transition temperature Tc as a function of distance from the boundary plane.

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GLAG theory for superconducting property variations with A15 composition in Nb3Sn wires

Cited by 16 publications

References 35 publications

Surface Impedance Measurements on Nb<inline-formula> <tex-math notation="LaTeX">$_{3}$</tex-math> </inline-formula>Sn in High Magnetic Fields

Surface Impedance Measurements on Nb<inline-formula> <tex-math notation="LaTeX">$_{3}$</tex-math> </inline-formula>Sn in High Magnetic Fields

Current Flow and Flux Pinning Properties of YBCO Foam Struts

$\textit{Ab Initio}$ Theory of the Impact from Grain Boundaries and Substitutional Defects on Superconducting Nb$_3$Sn

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