Grain boundary studies in YBCO processed by the liquid phase removal method

YBCO bulk materials were crystallized by a multi-seeded melt growth process. Up to four biaxial oriented Sm-123 seeds were placed on the top of rectangular shaped YBCO bars (up to ). The oriented grown single grains are joined by partially coherent grain boundaries with an improved current transport capability and high levitation forces with overall values of 55-65 N. Segregation of nonsuperconducting rest melt and microcracks limit the current transport across the grain boundary.

Section: Introductionsupporting

confidence: 89%

Multi-seeded melt crystallization of YBCO bulk material for cryogenic applications

Schätzle¹,

Krabbes²,

Stöver³

et al. 1999

“…Therefore, boundary control techniques to fabricate large samples by a simple and economic heat treatment are receiving more interest [6][7][8][9][10]. Joining and multiseeding techniques [6,7,10] have been already tried in attempt to make clean and electronically transparent grain boundaries.…”

Section: Introductionmentioning

confidence: 99%

“…In the latter case, a critical current density of ∼10 4 A cm −2 was reported across the boundary in zero magnetic field. Also, with the liquid removal method [8,9], a critical current density of ∼10 4 A cm −2 was obtained in spite of the existence of high-angle grain boundaries. Grain boundaries in YBCO superconductors are known as weak links in current transportation because of the short coherence length.…”

Section: Introductionmentioning

confidence: 99%

“…Multiseeding has additional advantages as well as a time-saving effect. It does not need any additional post-MTG heat treatment compared with joining processes [6,7], and the crystallographic orientation of each grain can be controlled compared with the liquid removal method [8,9]. Additionally, variation in sample shape is possible by arranging the seeds properly.…”

Section: Introductionmentioning

confidence: 99%

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Top-seeded melt growth of Y-Ba-Cu-O superconductor with multiseeding

Jee

Kim

Sung

et al. 2000

100

Y-Ba-Cu-O superconductors were prepared by the top-seeded melt growth process with multiseeding technique. By using several seeds at the same time, large samples could be fabricated in a short time with simple heat treatment. However, the samples fabricated by the normal multiseeding technique show a rapid decrease of trapped magnetic field value across the grain boundaries because of the residual liquid layer. To remove the residual liquid layer, various types of multiseeding were newly suggested. The optimum result was obtained when the seeds were arranged without spacing. The individual grains were combined as a single domain and did not show any deterioration of magnetic properties at the boundary. The formation mechanism of a well-combined single domain by the multiseeding technique is discussed.

“…Grain boundary analysis was performed on these samples using optical twin trace methods to measure the misorientation of the a-b planes (kink angle) across the boundary [11]. Three high current capacity samples were used for this analysis.…”

Section: Grain Boundary Analysismentioning

confidence: 99%

Recent developments in melt texturing of 123 compounds

Saláma

Sathyamurthy

1998

Self Cite

The melt texturing process, which has been under development since 1988, is now well established in producing components such as levitators and permanent magnets which can be used at liquid-nitrogen temperature. Recently, major accomplishments have been achieved which suggest that bulk applications of this process in industry are quite feasible. Studies have been performed to increase the rate of texturing and to achieve high critical currents through high-angle grain boundaries. These new developments, individually or in combination, can make the processing of 123 superconducting materials faster, more efficient, more robust, and also scalable, in order to satisfy industrial needs. In this paper, two of the new developments in melt texturing will be described, and some of the approaches to potential bulk applications will be reviewed.