Visualization of the grain structure in the filament cross sections
                    of uniaxially textured high J
               <sub>c</sub> Bi-2223
                    tapes

Kametani, F.; Oloye, Temidayo Abiola; Jiang, J.; Osabe, Goro; Kobayashi, Shinichi

doi:10.7567/1882-0786/ab347e

Cited by 4 publications

(5 citation statements)

References 34 publications

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“…We now should revisit the comparison of Bi-2212 and Bi-2223 in the context of the Railway Switch [24] and Brick Wall [22] models to explore how they might develop significantly different non-hysteretic and hysteretic J c (H) characteristics. It was clearly shown in Figure 5 [15]. As in reference [10], many Railway Switch type SCTILT intersections in which small angle c-axis tilt grain boundaries obliquely butt into the basal plane of another are present in these Bi-2223 tapes.…”

Section: Discussionmentioning

confidence: 61%

“…2223 tape [15]. Moreover, the Bi-2212 wires lack the hysteretic field-increasing, field-decreasing, weak-link signature displayed by Bi-2223 [10].…”

Section: Introductionmentioning

confidence: 97%

“…The round-wire form is very desirable for magnet applications because it allows the conductor to be produced in a low-hystereticloss, multi-filamentary, twisted state in a macroscopically isotropic architecture that provides high magnetic field quality. The paradox of round wire Bi-2212 is that it is now possible to make it with some 6 times higher J c [12][13][14] than carefully textured Bi-2223 tapes [15,16], a conundrum that seems to violate much of our hard-won understanding of HTS grain boundaries over the last 30 years.…”

Section: Introductionmentioning

confidence: 99%

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The Conundrum of Strongly Coupled Supercurrent Flow in Both Under- and Over-doped Bi-2212 Round Wires

Oz,

Jiang,

Matras

et al. 2021

Preprint

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Understanding what makes Bi2Sr2Ca1Cu2Ox (Bi-2212) the only high critical current density (Jc), high temperature superconductor (HTS) capable of being made as a round wire (RW) is important intellectually because high Jc RW Bi-2212 breaks the paradigm that forces biaxially textured REBCO and uniaxially textured (Bi,Pb)2Sr2Ca2Cu3Ox (Bi-2223) into tape geometries that reproduce the strong anisotropy of the native crystal structure and force expensive fabrication routes to ensure the best possible texture with minimum density of high angle grain boundaries. The biaxial growth texture of Bi-2212 developed during a partial melt heat treatment should favor high Jc, even though its ∼15 • full width at half maximum (FWHM) grain-to-grain misorientation is well beyond the commonly accepted strong-coupling range. Its ability to be strongly overdoped should be valuable too, since underdoped cuprate grain boundaries are widely believed to be weakly linked. Accordingly, we here study property changes after oxygen underdoping the optimized, overdoped wire. While Jc and vortex pinning diminish significantly in underdoped wires, we were not able to develop the prominent weak-link signature (a hysteretic Jc(H) characteristic) evident in even the very best Bi-2223 tapes with a ∼ 15 • FWHM uniaxial texture. We attribute the high Jc and lack of weak link signature in our Bi-2212 round wires to the high-aspect ratio, large-grain, basalplane-faced grain morphology produced by partial-melt processing of Bi-2212 which enables c-axis Brick-Wall current flow when ab-plane transport is blocked. Since we have elsewhere concluded that only a very small fraction of the filament cross-section carries the current, we conclude that the presently optimized biaxial texture of Bi-2212 intrinsically constitutes a strongly coupled current path, regardless of its oxygen doping state.

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Section: Discussionmentioning

confidence: 61%

“…2223 tape [15]. Moreover, the Bi-2212 wires lack the hysteretic field-increasing, field-decreasing, weak-link signature displayed by Bi-2223 [10].…”

Section: Introductionmentioning

confidence: 97%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

The Conundrum of Strongly Coupled Supercurrent Flow in Both Under- and Over-doped Bi-2212 Round Wires

Oz,

Jiang,

Matras

et al. 2021

Preprint

Self Cite

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“…Figures 8(a) and (b) are the EBSD maps of samples, and the color code can be found in the legends attached in the small figures, in which red color presents the [001] direction of Ba-122 grains. Figures 8(c) and (d) display the out-of-plane misorientations for the superconducting cores, which are defined by the direction of c-axis alignment with respect to normal direction of the tape [35]. The fractions of misorientations within 9 • for GT-20 samples and GT-150 samples are 19.0% and 16.6%, respectively.…”

Section: Resultsmentioning

confidence: 99%

Effects of precursor powder particle size on the powder-in-tube Ba_1−xK_xFe₂As₂ superconducting tapes

Chen

Liu

et al. 2022

Supercond. Sci. Technol.

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In this paper, we studied the effects of precursor powder particle size on Ag-sheathed powder-in-tube Ba1−xKxFe2As2 (Ba-122) superconducting tapes. Precursor powders with different particle sizes were prepared by changing the grinding time of calcined bulks. We systematically investigated the relationship between particle size of precursor powder, microstructure and superconducting properties of tapes. For short grinding time, the uneven particle size distribution damages the interface between Ba-122 core and Ag sheath, resulting in distinct sausage effect and decline of mass density of the Ba-122 core, causing severe fluctuation for the transport current density (Jc). Then with the extension of grinding time, the transport Jc becomes more uniform due to the improved homogeneity but lower with the reduction of average particle size from 21.48 to 9.49 μm. The Jc of samples made with precursor powders by grinding 20 minutes reaches 5 × 104 A/cm2at 4.2 K and 10 T. It has been shown that the coarse grains are easier to align along the rolling direction of tapes and lead to a higher degree of c-axis texture. Our results demonstrated the importance of controlling the homogeneity and particle size of precursor powders in achieving superior Jc for iron-based superconducting tapes.

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“…Other methods for controlling the J c of the intermediate layer can be effective in producing a high I c . The significant parameters for controlling J c include constituent phase [2], c-axis grain alignment [35], chemical composition [22,23], and grain boundary structure [36]. Among them, improving c-axis grain alignment is promising because the grain alignment of the intermediate layer was poor, as shown in 3.2.3.…”

Section: Achieving High Ic In the Bi-2223 Superconducting Jointmentioning

confidence: 99%

The effect of intermediate layer densification on the critical current of a Bi-2223 superconducting joint

Takeda

Nishijima

Inoue

et al. 2023

Supercond. Sci. Technol.

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The effect of intermediate layer densification on the critical current (I c) of Bi-2223 superconducting joints was quantitatively studied. First, we evaluated the phase purity, density, and intergrain critical current density (J c) of Bi-2223 thick film samples simulating the intermediate layer. The samples were uniaxially pressed to increase the film density. After two heat treatments of the pressed film, an increase in J c was achieved. Second, we fabricated superconducting joints by synthesizing an intermediate layer between two Bi-2223 tapes. Applying a uniform uniaxial pressure on the joint resulted in the formation of a homogenous structure. This process enables the reproducible fabrication of superconducting joints with high n values. The I c of the superconducting joint was increased by intermediate pressing and two heat treatments. However, pressing at high pressures can mechanically damage filaments in the Bi-2223 tapes, leading to a decrease in I c. Sample characterization showed that the optimum intermediate pressing pressure range to produce high I c was 1.5–2 × 108 Pa. We confirmed that pressing densified the intermediate layer of the superconducting joints. Our experimental results and analyses reveal that densification of the intermediate layer increases the I c of Bi-2223 superconducting joints.

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Visualization of the grain structure in the filament cross sections of uniaxially textured high J _c Bi-2223 tapes

Cited by 4 publications

References 34 publications

The Conundrum of Strongly Coupled Supercurrent Flow in Both Under- and Over-doped Bi-2212 Round Wires

The Conundrum of Strongly Coupled Supercurrent Flow in Both Under- and Over-doped Bi-2212 Round Wires

Effects of precursor powder particle size on the powder-in-tube Ba_1−xK_xFe₂As₂ superconducting tapes

The effect of intermediate layer densification on the critical current of a Bi-2223 superconducting joint

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Visualization of the grain structure in the filament cross sections of uniaxially textured high J c Bi-2223 tapes

Cited by 4 publications

References 34 publications

The Conundrum of Strongly Coupled Supercurrent Flow in Both Under- and Over-doped Bi-2212 Round Wires

The Conundrum of Strongly Coupled Supercurrent Flow in Both Under- and Over-doped Bi-2212 Round Wires

Effects of precursor powder particle size on the powder-in-tube Ba1−xKxFe2As2 superconducting tapes

The effect of intermediate layer densification on the critical current of a Bi-2223 superconducting joint

Contact Info

Product

Resources

About

Visualization of the grain structure in the filament cross sections of uniaxially textured high J _c Bi-2223 tapes

Effects of precursor powder particle size on the powder-in-tube Ba_1−xK_xFe₂As₂ superconducting tapes