Diffusion in A15 Nb3Sn: An atomistic study

Oh, Seogil; Seol, Donghyuk; Jeong, Yang-Jin; Na, Sin-Hye; Kim, Jiman; Ko, Won-Seok; Jeon, Jong Bae; Lee, Byeong-Joo

doi:10.1016/j.actamat.2022.118050

Cited by 8 publications

(3 citation statements)

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“…Previous experiments using Kirkendell markers have shown that Sn is the fastest diffusing species in the A15 compound [39], despite first principles calculations predicting Nb as the faster diffusing species [37]. This discrepancy has been explained by assuming grain boundary diffusion dominates the overall transport process in polycrystalline Nb 3 Sn [40]. The high Nb regions we are reporting in these RRP ® samples suggest incomplete diffusion of Sn into the centre of the grains, which is additional evidence for the dominance of grain boundary diffusion as the primary atomic transport process during the formation of polycrystalline Nb 3 Sn.…”

Section: Discussionmentioning

confidence: 97%

Understanding the nanoscale chemistry of as-received and fast neutron irradiated Nb₃Sn RRP^® wires using atom probe tomography

Wheatley

Baumgartner

Eisterer

et al. 2023

Supercond. Sci. Technol.

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Atom Probe Tomography has been used to study the effect of fast neutron irradiation on the local chemistry of Nb3Sn samples. Two RRP® wires doped with 2 at% Ti were analysed, one in the as-received condition and the other irradiated to a neutron fluence (E>0.1MeV) of 2.82x1022 m-2 in the TRIGA-II reactor. The irradiated sample had a reduced Tc, an increase in Fp, a shift in the peak of the Fp curve suggesting the introduction of secondary point pinning, and an increase in the estimated scaling field B*. Atom Probe Tomography analysis has shown that polycrystalline Nb3Sn has three distinct regions of composition, near stoichiometry Nb3Sn (low Nb), regions with a higher Nb content than expected in equilibrium Nb3Sn (high Nb) and grain boundaries. The summed composition of these three regions lies within the Nb3Sn phase for both the as-received and irradiated samples. The distinct regions of high Nb Nb3Sn demonstrate incomplete diffusion in the as-received sample, and the reduction in volume of these high Nb regions after irradiation implies significant radiation induced diffusion has occurred. The occurrence presence of other features in the atomic-scale chemistry, such as the extent of Cu segregation at grain boundaries, and to three types of dislocation array, and unreacted Nb nanoparticles, are compared between samples.

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Section: Discussionmentioning

confidence: 97%

Understanding the nanoscale chemistry of as-received and fast neutron irradiated Nb₃Sn RRP^® wires using atom probe tomography

Wheatley

Baumgartner

Eisterer

et al. 2023

Supercond. Sci. Technol.

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show abstract

“…This behavior implies that nucleations, in the presence of pre-deposits wetting on the Nb surface during annealing, likely originate at multiple sites, and the growth develops without being directed to a specific growth direction. In contrast, the heterogeneous nucleation during vapor diffusion strongly relies on the Nb surface conditions, the Sn-vapor adsorption preference, and the Sn diffusion limitations, generating vertically abnormal grains [32,38,44,45]. This difference in nucleation mechanism may deserve further in situ investigations.…”

Section: Structural Characterizations and Superconducting Propertiesmentioning

confidence: 99%

“…Likewise, inadequate Sn sources and slow supply rates produce initially Sn-deficient grains [30,31] and calculated [32,33] data). ('bad' Nb 3 Sn) following the 18 at.%-Sn boundary in the phase diagram; subsequently, slow Sn diffusion within these grains kinetically limits their conversion into stoichiometric 'good' Nb 3 Sn [32,38,44,45]. Thus, we intend to design a deposition process that ensures a sufficient amount and rate of Sn supply during nucleation.…”

Section: Introductionmentioning

confidence: 99%

Smooth, homogeneous, high-purity Nb₃Sn superconducting RF resonant cavity by seed-free electrochemical synthesis

Sun,

Baraissov,

Porter

et al. 2023

Supercond. Sci. Technol.

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Workbench-size particle accelerators, enabled by Nb3Sn-based superconducting radio-frequency (SRF) cavities, hold the potential of driving scientific discovery by offering a widely accessible and affordable source of high-energy electrons and X-rays. Thin-film Nb3Sn RF superconductors with high quality factors, high operation temperatures, and high-field potentials are critical for these devices. However, surface roughness, non-stoichiometry, and impurities in Nb3Sn deposited by conventional Sn-vapor diffusion prevent them from reaching their theoretical capabilities. Here we demonstrate a seed-free electrochemical synthesis that pushes the limit of chemical and physical properties in Nb3Sn. Utilization of electrochemical Sn pre-deposits reduces the roughness of converted Nb3Sn by five times compared to typical vapor-diffused Nb3Sn. Quantitative mappings using chemical and atomic probes confirm improved stoichiometry and minimized impurity concentrations in electrochemically synthesized Nb3Sn. We have successfully applied this Nb3Sn to the large-scale 1.3 GHz SRF cavity and demonstrated ultra-low BCS surface resistances at multiple operation temperatures, notably lower than vapor-diffused cavities. Our smooth, homogeneous, high-purity Nb3Sn provides the route toward high efficiency and high fields for SRF applications under helium-free cryogenic operations.

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Formation of columnar grains during diffusional growth of Nb3Sn layer and its suppression

Oh,

Jeong,

et al. 2024

Acta Materialia

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Diffusion in A15 Nb3Sn: An atomistic study

Cited by 8 publications

References 50 publications

Understanding the nanoscale chemistry of as-received and fast neutron irradiated Nb₃Sn RRP^® wires using atom probe tomography

Understanding the nanoscale chemistry of as-received and fast neutron irradiated Nb₃Sn RRP^® wires using atom probe tomography

Smooth, homogeneous, high-purity Nb₃Sn superconducting RF resonant cavity by seed-free electrochemical synthesis

Formation of columnar grains during diffusional growth of Nb3Sn layer and its suppression

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Diffusion in A15 Nb3Sn: An atomistic study

Cited by 8 publications

References 50 publications

Understanding the nanoscale chemistry of as-received and fast neutron irradiated Nb3Sn RRP® wires using atom probe tomography

Understanding the nanoscale chemistry of as-received and fast neutron irradiated Nb3Sn RRP® wires using atom probe tomography

Smooth, homogeneous, high-purity Nb3Sn superconducting RF resonant cavity by seed-free electrochemical synthesis

Formation of columnar grains during diffusional growth of Nb3Sn layer and its suppression

Contact Info

Product

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About

Understanding the nanoscale chemistry of as-received and fast neutron irradiated Nb₃Sn RRP^® wires using atom probe tomography

Understanding the nanoscale chemistry of as-received and fast neutron irradiated Nb₃Sn RRP^® wires using atom probe tomography

Smooth, homogeneous, high-purity Nb₃Sn superconducting RF resonant cavity by seed-free electrochemical synthesis