Effects of oxygen content on the superconducting properties of melt-textured LRE123 superconductors

Chikumoto, N.; Ozawa, Shinobu; Yoo, Sang‐Im; Hayashi, N.; Murakami, Masato

doi:10.1016/s0921-4534(97)00115-9

Cited by 27 publications

(9 citation statements)

References 5 publications

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“…However, the positive influence of oxygen vacancies remained only on a laboratory level and could not be fully employed in applications because with increasing oxygen deficiency a reduction of T c was coupled. 9 In LRE-123 materials, the microstructure study revealed a compositional fluctuation on the nanometer scale that had a similar positive effect on the secondary peak as oxygen deficiency. 10,11 This fluctuation originated in solid solution of LRE atoms with Ba ''LRE-123ss.''…”

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confidence: 98%

Vortex pinning by mesoscopic defects: A way to levitation at liquid oxygen temperature

Muralidhar

Sakai

Jirsa

et al. 2003

Applied Physics Letters

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The addition of long-term Zr 2 O 3 -ball milled Gd 2 BaCuO 5 particles to a standard (Nd,Eu,Gd)Ba 2 Cu 3 O y superconductor led to a spontaneous formation of extremely small ͑20-50 nm͒ Zr-rich ͑Nd,Eu,Gd͒-Ba-Cu-O particles during the melt-growth process. This pinning medium, approaching the interesting physical limit of point-like pins from the side of large normal ones, dramatically enhanced supercurrents up to 90 K, both in low and intermediate fields. As a result, levitation experiment could be performed with liquid oxygen as a coolant. The particle size effect resemblance with fast neutron irradiation of RE-Ba-Cu-O single crystals is discussed.

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confidence: 98%

Vortex pinning by mesoscopic defects: A way to levitation at liquid oxygen temperature

Muralidhar

Sakai

Jirsa

et al. 2003

Applied Physics Letters

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“…The size of these clusters is comparable to the vortex core size and, thus, these clusters can serve as pointlike pins, effectively enhancing J c , especially at intermediate and high fields and increasing thus B irr value. Concentration of this type of pin is controlled by a different mechanism than oxygen deficiency [4]. Therefore, Nd-123 samples could be optimally oxygenated to achieve maximum T c , without any loss of pinning efficiency.…”

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New Type of Vortex Pinning Structure Effective at Very High Magnetic Fields

et al. 2002

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We report on a new type of correlated nanometer-scale pinning structure observed in a melt-processed (Nd0.33Eu0.38Gd0.28)Ba(2)Cu(3)O(y) (NEG-123). It consists of NEG/Ba-rich clusters in the stoichiometric NEG-123 matrix forming a lamellar array with a period of a few nanometers. These lamellas appear within regular twins, thus representing their fine substructure-sometimes straight, sometimes wavy. This new material structure correlates well with the significant enhancement of pinning at high fields, represented by irreversibility field above 14 T at 77 K (B parallel c). We believe that the new pinning medium enables one to significantly broaden the limits for high-field applications.

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“…For oxygenation, some melt-textured discs and the small specimens were annealed in flowing oxygen (99.9% pure) at 500 • C for 10 h, from 500 annealing temperature of 300 • C was selected for maximizing T c based on the reported results [31].…”

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Spatial variation in magnetic properties within large-grain Nd-Ba-Cu-O/Ag

Takebayashi

Murakami

2001

Supercond. Sci. Technol.

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We investigate the spatial variation in the superconducting properties of Nd-Ba-Cu-O/Ag large grains fabricated by a top-seeded melt growth process in controlled partial oxygen pressures of 0.01 atm and 0.001 atm. The results of magnetic measurements show that superconducting transition temperature and critical current vary with position in a large sample. It is found that such spatial variation in magnetic properties can be reduced when a sample is grown under a low oxygen partial pressure. It is also found that trapped field distributions of Nd-Ba-Cu-O/Ag large grains reflect their spatial variations in the magnetic properties. In order to enhance the trapped field, it is necessary to optimize the local magnetic properties in the vicinity of the central axis in large-grain materials.

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Effects of oxygen content on the superconducting properties of melt-textured LRE123 superconductors

Cited by 27 publications

References 5 publications

Vortex pinning by mesoscopic defects: A way to levitation at liquid oxygen temperature

Vortex pinning by mesoscopic defects: A way to levitation at liquid oxygen temperature

New Type of Vortex Pinning Structure Effective at Very High Magnetic Fields

Spatial variation in magnetic properties within large-grain Nd-Ba-Cu-O/Ag

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