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

Muralidhar, M.; Sakai, Naomichi; Jirsa, M.; Koshizuka, N.; Murakami, Masato

doi:10.1063/1.1634376

Cited by 45 publications

(38 citation statements)

References 21 publications

(29 reference statements)

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“…The analyzed spot of 2-3 nm in diameter enabled to unambiguously analyze even the smallest clusters. The quantitative analysis clarified that the large particles were Gd-211/Gd-rich-NEG-211, while the defects with size below 50 nm always contained a significant amount of Zr, in agreement with our earlier studies of the NEG-123 and SEG-123 systems (Muralidhar et al, 2003c;Muralidhar et al, 2004a). Recently, the exact chemical composition of these particles was determined as LREBa 2 CuZrO y (Muralidhar et al, 2003).…”

Section: Flux Pinning In Neg-123 Due To Nb 2 O 5 Nanoparticlessupporting

confidence: 72%

“…With the help of these ball-milled nanoparticles a new type of nano-scale Zr-rich NEG-Ba-Cu-O precipitates appeared in the final product, accompanied by an exceptional pinning enhancement in all high temperatures, up to vicinity of T c . As a result, this material showed very high critical current density at 90.2 K, the boiling temperature of liquid oxygen (Muralidhar et al, 2003c). With this material we could levitate a permanent magnet at 90.2 K. As a result, a remarkable flux trapping, by order of magnitude higher than the best classical hard magnets, was achieved.…”

Section: Introductionmentioning

confidence: 73%

“…For the first time the super-current density at 90 K was high enough to successfully levitate permanent magnet under liquid oxygen cooling (Muralidhar et al, 2003c).…”

Section: Nanometer-sized Second-phase Inclusions In Neg-123mentioning

confidence: 96%

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Nanoscale Pinning in the LRE-123 System - the Way to Applications up to Liquid Oxygen Temperature and High Magnetic Fields

Muralidhar¹,

Tomita²,

Jirsa³

2010

Superconductor

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Section: Flux Pinning In Neg-123 Due To Nb 2 O 5 Nanoparticlessupporting

confidence: 72%

Section: Introductionmentioning

confidence: 73%

See 1 more Smart Citation

Nanoscale Pinning in the LRE-123 System - the Way to Applications up to Liquid Oxygen Temperature and High Magnetic Fields

Muralidhar¹,

Tomita²,

Jirsa³

2010

Superconductor

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“…The low-field part of it is usually increased by "large" particles of secondary phases (in the micron and sub-micron scales). The smaller the secondary phase particles size, the stronger is the effect [6,7]. In the case of nanometric nonsuperconducting particles the J c enhancement is so strong that extends up to intermediate fields and at high temperatures (where the secondary peak becomes weak) it passes over the whole field range up to the irreversibility field.…”

Section: Introductionmentioning

confidence: 89%

Effect of oxygen annealing on magnetic performance of (Nd,Eu,Gd)Ba₂Cu₃O_ywith a lamelar pinning nanostructure

Jirsa

Rameš

Muralidhar

et al. 2009

J. Phys.: Conf. Ser.

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Abstract. The nanometer-scale correlated pinning disorder filling channels between regular twin boundaries in the melt-textured (Nd,Eu,Gd)Ba 2 Cu 3 O y composite is studied. Aligned with regular twin boundaries but tightly packed on nm-scale, this pinning medium is capable to significantly enhance pinning performance at high magnetic fields. We show that oxygen annealing plays a principal role in the formation mechanism of this defect type. It seems that the nanoscale lamelar structure is extremely sensitive to the oxygenation procedure and to the terminal temperature. IntroductionIn the LRE-Ba 2 Cu 3 O y compounds (LRE-123, LRE=light rare earth, Nd, Sm, Eu, Gd) much better vortex pinning environment can be created than in YBa 2 Cu 3 O y (Y-123) and thus they can carry significantly higher engineering currents [1][2][3]. Therefore, the LRE-123 bulks can trap the same magnetic field as Y-123 [4] but at higher temperatures or a higher magnetic field at the same temperature. It is commonly due to the additional source of point-like pins consisting of LRE/Ba solid solution nanometer scale clusters. Amount of this type of substitution is usually kept in an optimal range by growing the material in a reduced oxygen atmosphere [1][2][3] or by a slight excess of Cu over Ba in the starting powder [5]. This kind of pinning enhances mainly the secondary peak, the intermediate field range of J c -B dependence. The low-field part of it is usually increased by "large" particles of secondary phases (in the micron and sub-micron scales). The smaller the secondary phase particles size, the stronger is the effect [6,7]. In the case of nanometric nonsuperconducting particles the J c enhancement is so strong that extends up to intermediate fields and at high temperatures (where the secondary peak becomes weak) it passes over the whole field range up to the irreversibility field.In binary and ternary LRE-123 compounds variation in the mutual LRE ratio offers a natural tool how to manipulate with the local environment (say tensions) in the superconducting matrix. Due to different sizes of LRE ions their positions and concentrations are not exactly equivalent. It has been found that in a narrow range of the Nd:Eu:Gd ratio (around 33:38:28) the superconducting matrix is frustrated (in the positive sense from our point of view) so that a periodical correlated nanostructure appears [1]. It has either a zig-zag shape or, in the better case, it is planar, aligned with the regular twin boundaries and filling the channels between them. As the period of this new structure is typically a few nm, just in the range of the vortex core size, no wonder that a very strong pinning effect appears. This effect enhances critical currents at high magnetic fields and presents itself as a hump or shoulder

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“…Recently, a successful attempt was made to intentionally reduce size of the commercial Gd-211 powder by milling in acetone by means of Y 2 O 3 -ZrO 2 balls. In dependence of the milling time (0.5 to 4 hours), the particles had the average size from 200 to 70 nm [5,6]. An optimum concentration was found to be 40 mol% [5].…”

mentioning

confidence: 99%

Superconducting Permanent Magnets for High-temperature Operation

Jirsa

Muralidhar

2004

Czech J Phys

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LRE-BaIntroduction. The most promising materials for superconducting permanent magnets recruit from the LRE-Ba 2 Cu 3 O y family. The typical pinning structure consists of point-like disorder, 'large' particles of non-superconducting secondary phases, and twin structure. Point-like disorder, associated with collective pinning of individual vortices, enhances super-currents at intermediate magnetic fields. The secondary-phase particles, around one micrometer in size, are most effective vortex traps at low magnetic fields. Twin planes represent a specific correlated disorder that has a special effect on the J(B) profile, either reducing height of the secondary peak or filling the dip between the secondary and central peaks. In the present work we summarize recent results obtained on ternary RE-Ba 2 Cu 3 O y compounds, where three different light-rare-earth elements (La, Sm, Nd, Eu, Gd) occupy the rare-earth site.Experimental results. Although technology plays most important role in the recent achievements in this field, we have no space to go into details here. These can be found in [1].It has been verified that mixing together several LRE elements at the rare-earth site of the LRE-123 compounds hinders neither appearance of superconductivity nor the melt texture growth. In most cases such complex compounds behave like a single-LRE 123 material. In any case, the bulk ternary LRE-123 compounds produced by oxygen-control melt-growth method exhibit excellent electromagnetic

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

Cited by 45 publications

References 21 publications

Nanoscale Pinning in the LRE-123 System - the Way to Applications up to Liquid Oxygen Temperature and High Magnetic Fields

Nanoscale Pinning in the LRE-123 System - the Way to Applications up to Liquid Oxygen Temperature and High Magnetic Fields

Effect of oxygen annealing on magnetic performance of (Nd,Eu,Gd)Ba₂Cu₃O_ywith a lamelar pinning nanostructure

Superconducting Permanent Magnets for High-temperature Operation

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

Cited by 45 publications

References 21 publications

Nanoscale Pinning in the LRE-123 System - the Way to Applications up to Liquid Oxygen Temperature and High Magnetic Fields

Nanoscale Pinning in the LRE-123 System - the Way to Applications up to Liquid Oxygen Temperature and High Magnetic Fields

Effect of oxygen annealing on magnetic performance of (Nd,Eu,Gd)Ba2Cu3Oywith a lamelar pinning nanostructure

Superconducting Permanent Magnets for High-temperature Operation

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Effect of oxygen annealing on magnetic performance of (Nd,Eu,Gd)Ba₂Cu₃O_ywith a lamelar pinning nanostructure