Effects of Wire Diameter and Filament Size on the Processing Window of Bi-2212 Round Wire

Jiang, J.; Hossain, S.; Oloye, Temidayo Abiola; Oz, Yavuz; Barua, Shaon; Cooper, Jonathan M.; Miller, Evan; Huang, Yibing; Parrell, J.A.; Kametani, F.; Trociewitz, U.P.; Hellstrom, E. E.; Larbalestier, D. C.

doi:10.1109/tasc.2021.3055475

Cited by 19 publications

(10 citation statements)

References 27 publications

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“…The critical current was measured in transport at 4.2 K up to 15 T as reported in [20], finding that the engineering current density J E and so the critical current density J c have a clear variation with T max , similarly to what previously reported on the same conductor in [8]. The maximum J c is obtained at the lowest T max = 885 • C reaching 7115 A mm −2 at 5 T and 4.2 K. With a small increase of T max (887.5 1 and, in the following the samples will be identified by T max and/or their J c (5 T).…”

Section: Methodssupporting

confidence: 77%

“…Jiang et al demonstrated that, despite property variations caused by wire design or diameter, and quality of the precursor powers, J c generally reaches its maximum for the lowest possible T max that allows full melting. At higher T max there is a lower-J c plateau or one with a moderate decrease up to ∼896 • C [8]. At the lowest T max having maximum J c there is only limited filament bridging, but with increasing T max significant inter-filament connective bridges develop.…”

Section: Introductionmentioning

confidence: 96%

“…It is also made in kilometre-piece length with a relatively simple powder-in-tube (PIT) multifilamentary design [2,3] suitable for the realization of accelerator and research magnets at fields larger than 20 T [4][5][6][7]. To achieve its best performance, Bi-2212 wire has to undergo an overpressure heat treatment (OPHT) with multiple steps and multiple parameters, which affect both the microstructure and transport critical current density (J c ) [1,8,9]. It was recently showed that the quality of the precursor powder has a significant effect on the wire performance and on the narrow processing window on Bi-2212 [10,11].…”

Section: Introductionmentioning

confidence: 99%

“…One of the key OPHT parameters is the maximum HT temperature T max (typically set in the 885 • C-896 • C range), which also directly affects the time in the melt t melt . In fact t melt is defined as t 872 • C↓ -t 884 • C↑ , where t 884 • C↑ and t 872 • C↓ are respectively the times at which Bi-2212 starts melting on heating and starts solidifying on cooling [8,9,19]. In this step, together with Bi-2212 powder particles melting, there is also some dissolution of Ag from the sheath and penetration of liquid along Ag grain boundaries, which allow filament bridging to occur.…”

Section: Introductionmentioning

confidence: 99%

“…These are the features of the wire investigated here. The cross-sections of the samples in the present paper were recently characterized by scanning electron microscopy (similar to that in [8]) and by extensive x-ray diffraction to evaluate their grain texture [20], which revealed a systematic worsening of the [100] Bi-2212 texture with increasing T max . Some of the driving questions for this study of Bi-2212 wires are: Does 2212 show signs of granularity despite its good overall J c performance?…”

Section: Introductionmentioning

confidence: 99%

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Variation of effective filament diameter, irreversibility field, anisotropy, and pinning efficiency in Bi-2212 round wires

Tarantini,

Barua,

Oloye

et al. 2023

Supercond. Sci. Technol.

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In recent years Bi2Sr2CaCu2O x (Bi-2212) received increasing attention due to its round wire multifilamentary architecture, a unique feature in high-Tc superconductor. In fact, round wires are preferable for magnet designs, including solenoids for nuclear magnetic resonance (NMR) or research purpose and accelerator magnets. However, due to the narrow over-pressure heat treatment conditions necessary to obtain high Jc and to the peculiar microstructure of Bi-2212 wires, a full understanding of the correlations between the different properties has not yet been developed. In this paper we investigate the effect of a vital part of Bi-2212 optimization, the maximum heat-treatment temperature T max in the range of 885 °C–896 °C, on the variations of Jc , effective filament diameter d eff, anisotropy γ, INTER- and intra-grain irreversibility fields and pinning energies U 0, all critical parameters in unravelling the complex mix of vortex pinning and connectivity that ultimately determines the critical current density. We found that d eff of the higher Jc wires heat-treated at lower temperature is much smaller than for the lower Jc wires. Moreover, a systematic increase of the irreversibility field and a decrease of the intrinsic Bi-2212 anisotropy underpins the higher Jc . The analysis of the pinning energies reveals that there is little sample-to-sample variation in the INTER-grain pinning, whereas in all samples the intra-grain pinning has an enhancement below ∼40–45 K becoming more and more evident with increasing Jc . These results suggest that the overall Jc performance are not only related to the wire microstructure and connectivity, which obviously affect the INTER-grain properties, but they are also intimately related to the intrinsic and intra-grain properties such as γ and U 0.

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Section: Methodssupporting

confidence: 77%

Section: Introductionmentioning

confidence: 96%