Properties of grain boundaries in bulk, melt processed Y–Ba–Cu–O fabricated using bridge-shaped seeds

Shi, Yunhua; Durrell, John; Dennis, Anthony; Babu, N. Hari; Mancini, C.; Cardwell, D. A.

doi:10.1088/0953-2048/25/4/045006

Cited by 24 publications

(33 citation statements)

References 29 publications

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“…The shape of the trapped field distribution from PFM is determined by the length of bridge seeds and the boundary generated during the growth process. These results also agree with the experimental data presented previously in [19][20][21].…”

Section: Comparison Of Experimental and Numerical Simulation Resultssupporting

confidence: 93%

Pulsed field magnetization of 0°–0° and 45°–45° bridge-seeded Y–Ba–Cu–O bulk superconductors

Ainslie

Zeng

Mochizuki

et al. 2015

Supercond. Sci. Technol.

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Large, single-grain (RE)BCO (where RE = rare earth or Y) bulk superconductors with complicated geometries are required for a variety of potential applications, such as rotating machines, magnetic bearings and magnetic separation. As a consequence, the top multiseeded melt growth process has been studied over many years in an attempt to deliver large, single grains for practical applications. Among these techniques, the so-called bridgeseeding produces the best alignment of two seeds during melt processing of multi-seed samples. In this paper, the trapped field performance and magnetic flux dynamics of two bridge-seeded, multi-seed samples magnetized by pulsed field magnetization (PFM) are analysed: one with a 45⁰-45⁰ and another with a 0⁰-0⁰ bridge seed. Based on an analysis of the flux penetration across the seeds and in-between the seeds of the 45⁰-45⁰ multi-seed sample, an estimated J c distribution over the ab-plane was determined, which provides the basis for further analysis via numerical simulation. A 3D finite-element model, developed to qualitatively reproduce and interpret the experimental results, was employed to investigate the influence of the length of the bridge seed for such multi-seed samples. The simulation results agree well with the observed experimental results, in that the multi-seed sample's particular inhomogeneous J c distribution acts to distort the trapped field profile from a traditional conical Bean's profile, which is determined by the length and direction of the bridge seed on the bulk surface.Keywords: bulk superconductors, multi-seeding, bridge-shaped seeds, trapped field magnets, pulsed field magnetization, numerical modelling, finite element method (FEM) modelling c c c J J J x y z J J J J    .

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Section: Comparison Of Experimental and Numerical Simulation Resultssupporting

confidence: 93%

Pulsed field magnetization of 0°–0° and 45°–45° bridge-seeded Y–Ba–Cu–O bulk superconductors

Ainslie

Zeng

Mochizuki

et al. 2015

Supercond. Sci. Technol.

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“…that the trapped field of the samples fabricated using 45°–45° bridge seeds is less sensitive to bridge length than for samples fabricated using 0°–0° bridge seeds. The previous study of samples fabricated using different precursor powders suggested that trapped field decreases with increasing length of bridge seed. Samples seeded with both 0°–0° and 45°–45° bridge seeds exhibit two peaks in their trapped field profiles for a bridge length of 10 mm, as shown for samples 4 and 12 in Fig.…”

Section: Resultsmentioning

confidence: 95%

“…The technique works because the two seeds (i.e., the two legs of the bridge) are cut notionally from a single parent grain, which is also fabricated by melt processing. Most recently, we have developed a 0°–0° bridge‐seeding technique in which the angles between the direction of the long axis of the bridge and the a direction [corresponding to the (100) direction for the tetragonal Y–Ba–Cu–O (YBCO) phase] of the two seeds are 0° and 0°, respectively . Similarly, we have also studied bridge seeding using 45°–45° bridge seeds .…”

Section: Introductionmentioning

confidence: 99%

A Comparison of 0°–0° and 45°–45° bridge‐Seeded, YBCO single grains

et al. 2013

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A variety of multiseeding techniques have been investigated over the past 20 yr in an attempt to enlarge bulk (RE)BCO superconducting samples fabricated by the top-seeded melt growth (TSMG) process for practical applications. Unfortunately, these studies have failed to establish whether technically useful values of trapped field can be achieved in multiseeded bulk samples. In this work specially designed, 0°-0°and 45°-45°bridge seeds of different lengths have been employed to produce improved alignment of the seeds during the TSMG process. The ability of these bridge-seeded samples to trap magnetic field, which is the key superconducting property for practical applications of bulk (RE)BCO, is compared for the samples seeded using 0°-0°and 45°-45°bridge seeds of different lengths. The grain boundaries produced by these bridge seeds are analyzed in detail, and the similarities and differences between the two bridge-seeding processes are discussed.

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“…We have developed a novel, bridge-seeding technique to improve significantly the alignment between seeds in the top multiseeded melt growth (TMSMG) process [10] [11], which minimises any misinterpretation of the properties of the multi-seeded sample that may be associated with seed misalignment, rather than with grain growth. We reported recently that the effect of bridge length of 0° -0° orientated bridge-seeds on trapped field and J c and concluded that such an alignment of seeds is effective for the enlargement of single (RE)BCO grains for 0° -0° bridge-seeds of length up to 8 mm [12]. However, grain boundaries containing impurities (such as solidified liquid phases) still exist in these samples at the interface of the grains grown from the two legs of the bridgeseeds.…”

Section: Introductionmentioning

confidence: 96%

Bulk YBCO seeded with 45°–45° bridge-seeds of different lengths

Shi¹,

Durrell²,

Dennis³

et al. 2012

Supercond. Sci. Technol.

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Abstract. Single grain, (RE)BCO bulk superconductors in large or complicated geometries are required for a variety of potential applications, such as motors and generators and magnetic shielding devices. As a result, top, multi-seeded, melt growth (TMSMG) has been investigated over the past two years in an attempt to enlarge the size of (RE)BCO single grains specifically for such applications. Of these multi-seeding techniques, so-called bridge seeding provides the best alignment of two seeds in a single grain growth process. Here we report, for the first time, the successful growth of YBCO using a special, 45° -45°, arrangement of bridge-seeds. The superconducting properties, including trapped field, of the multi-seeded YBCO grains have been measured for different bridge lengths of the 45° -45° bridge-seeds. The boundaries at the impinging growth front and the growth features of the top, multi-seeded surface and cross-section of the multiseeded, samples have been analysed using optical microscopy. The results suggest that an impurity-free boundary between the two seeds of each leg of the bridgeseed can form when 45° -45° bridge-seeds are used to enlarge the size of YBCO grains.

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Properties of grain boundaries in bulk, melt processed Y–Ba–Cu–O fabricated using bridge-shaped seeds

Cited by 24 publications

References 29 publications

Pulsed field magnetization of 0°–0° and 45°–45° bridge-seeded Y–Ba–Cu–O bulk superconductors

Pulsed field magnetization of 0°–0° and 45°–45° bridge-seeded Y–Ba–Cu–O bulk superconductors

A Comparison of 0°–0° and 45°–45° bridge‐Seeded, YBCO single grains

Bulk YBCO seeded with 45°–45° bridge-seeds of different lengths

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