Cracking and oxygenation of YBaCuO bulk superconductors: application to c-axis elements for current limitation

Isfort, D.; Chaud, X.; Tournier, R.; Kapelski, G.

doi:10.1016/s0921-4534(03)00740-8

Cited by 41 publications

(47 citation statements)

References 37 publications

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“…For good performance in applications the material has to be mechanically resistant in order to withstand large thermal stresses during cooling/heating cycles and during magnetization [1]- [4]. Unfortunately YBa 2 Cu 3 O 7 compound is inherently brittle therefore it is sensitive to cracking [5].…”

Section: Methodsmentioning

confidence: 99%

Oxygenation Induced Cracking in YBCO Bulk Superconductors

Diko

2004

Czech J Phys

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It is shown that the a/b-and c-macrocracks starts to form on the surface of YBCO bulk superconductors at the initial stage of oxygenation. Shortening of the Y123 c-and (a + b)/2-lattice parameters with increasing oxygen concentration induces tensile stresses on oxygenated layer and causes its cracking. PACS : 74.72.BkTop seeded melt-grown (TSMG) bulk single-grain YBa 2 Cu 3 O 7 /Y 2 BaCuO 5 (Y123/211) superconductors are highly attractive for practical applications (as well as bulks where Y is replaced by rare earth (RE) element). For good performance in applications the material has to be mechanically resistant in order to withstand large thermal stresses during cooling/heating cycles and during magnetization [1]- [4]. Unfortunately YBa 2 Cu 3 O 7 compound is inherently brittle therefore it is sensitive to cracking [5]. In this contribution we summarize our latest results on the cracking associated with oxygenation of TSMG samples .The study was performed on the TSMG single-grain bulks, which were annealed at 900 • C in oxygen for 1 hour and cooled down in argon with the cooling rate 600 • C/hour, to have starting tetragonal samples with low and defined oxygen content. For further treatment, bars of 2 x 2 mm 2 cross-section and with bar walls parallel to the a/c-planes were cut and oxygenated at different temperatures in a tubular furnace. Heating to and cooling from the oxygenation temperature was carried out in Ar atmosphere. Samples were oxygenated in a flow of oxygen. The microstructure was studied by optical microscopy.2 Results and discusion 1. a/b-macrocracks. The oxygenation process was very inhomogeneous at lower temperatures (Fig. 1a, b). Cracks, which were formed during oxygenation, provided a path for oxygen flow to the sample and faster transformation to the orthorhombic state along the a/b-macrocracks and consequently enhanced crack propagation. At higher temperatures the oxygenated layer becomes more regular (Fig. 1c).

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Section: Methodsmentioning

confidence: 99%

Oxygenation Induced Cracking in YBCO Bulk Superconductors

Diko

2004

Czech J Phys

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“…But c-axis elements were shown recently to be very performing for current limitation [9], provided the cracks are suppressed, since the current is flowing in that case perpendicular to the cracks. By a progressive oxygenation process (details can be found in [10]), the oxygen gradients can be maintained below the limit where they induce cracks. But this strategy is limited by the oxygen diffusion: only thin samples, i.e.…”

Section: Introductionmentioning

confidence: 99%

Isothermal growth of large YBaCuO single domains through an artificial array of holes

Chaud

Meslin

Noudem

et al. 2005

Journal of Crystal Growth

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“…The recently reported [41][42][43][44][45] hole-patterned YBa2Cu3Oy (Y123) bulks with improved superconducting properties are highly interesting from the points of view of material quality and their variety of application. It is well known that the core of plain bulk superconductors needs to be fully oxygenated, and some defects like cracks, pores and voids [46,47] must be suppressed in order that the material can trap a high magnetic field or else carry a high current density. Some previous studies [48][49][50][51] demonstrated that, by filling the cracks, enhancing thermal conductivity or by reinforcing the YBCO bulk material, the properties can be improved and a trap field of up to 17 T at 29 K can be reached.…”

Section: Gd211 Bazro3mentioning

confidence: 99%

“…It was difficult to oxygenate the bulk sample with a big diameter and in this case the oxygen should diffuse into the core of the bulk. Generally, the big samples are annealed under oxygen at 400-450 °C between 150 to 600 hours [42,46,53,54]. These annealing dwell times are so long in order to allow for oxygen diffusion until the core of the monolith bulk materials.…”

Section: Gd211 Bazro3mentioning

confidence: 99%