Flux creep measurements in shocked YBa2Cu3O7 and La1.85Sr0.15CuO4

Sakaguchi, Yoshiyuki; Kikuchi, Masae; Kobayashi, Norio; Kusaba, Keiji; Fukuoka, Kazuya; Minagawa, Yasushi; Syono, Yasuhiko

doi:10.1016/0921-4534(91)91383-f

“…We can see that post annealing the as-shocked specimen leads to an increase in M, and that the annealing temperature of 800 • C is the most effective in introducing pinning centres. Characteristic features of shock compaction are the advantages of densification mentioned above and the introduction of dislocations which significantly enhance the flux pinning energy [6,7,11,12].…”

Section: Resultsmentioning

confidence: 99%

“…The temperature increase is generated only along the grain boundaries without affecting the inside of each grain [5]. The improvement of connectivity by shock densification [4,5] or the introduction of pinning sites by shock effects [6,7] is thought to be effective in achieving better superconducting characteristics. Bi 2 Sr 2 CaCu 2 O y (B2212) and Bi 1.65 Pb 0.35 Sr 2 Ca 2 Cu 3 O y (Bi2223) have unique layered structures and cleave easily along the BiO plane, like mica.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Output Characteristics of Solar-Power-Driven Thermionic Energy Converter

Oginö

¹

,

Muramatsu

²

,

Kando

³

2004

Jpn. J. Appl. Phys.

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Shock compaction experiments were carried out for Bi2223 to prepare a dense, oriented bulk specimen. The shocked specimen exhibited a high degree of crystallographic orientation and a high density, above 96%. The optimal condition of the crystallographic orientation was attained at a shock pressure of 5 GPa and at annealing temperatures between 750 and 800 • C. The post annealing of a specimen shocked at 5 GPa was effective in increasing M, indicating the introduction of pinning sites. The magnetic torque measurements showed that a high degree of orientation was attained and many pinning centres were induced by the shock loading.

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“…We can see that post annealing the as-shocked specimen leads to an increase in M, and that the annealing temperature of 800 • C is the most effective in introducing pinning centres. Characteristic features of shock compaction are the advantages of densification mentioned above and the introduction of dislocations which significantly enhance the flux pinning energy [6,7,11,12].…”

Section: Resultsmentioning

confidence: 99%

Consolidation of Bi-Sr-Ca-Cu-O superconductors by the shock-loading method

Kikuchi

¹

,

Faqir

²

,

Kawamata

³

et al. 2000

Supercond. Sci. Technol.

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Shock compaction experiments were carried out for Bi2223 to prepare a dense, oriented bulk specimen. The shocked specimen exhibited a high degree of crystallographic orientation and a high density, above 96%. The optimal condition of the crystallographic orientation was attained at a shock pressure of 5 GPa and at annealing temperatures between 750 and 800 • C. The post annealing of a specimen shocked at 5 GPa was effective in increasing M, indicating the introduction of pinning sites. The magnetic torque measurements showed that a high degree of orientation was attained and many pinning centres were induced by the shock loading.

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“…A few efforts to utilize dynamic or shock-wave methods for introducing defects which would then act as pinning centres in superconductive copper oxides have also been reported, and in some cases the magnetic properties were indeed found to be improved by the shock loading [105][106][107]. However, to avoid breakage of the CuO 2 planes caused by shock waves would be a prime requirement for these methods to be employed for application.…”

Section: Shock-wave Methodsmentioning

confidence: 99%

Application of high-pressure techniques: stabilization and oxidation-state control of novel superconductive and related multi-layered copper oxides

Yamauchi

¹

,

Karppinen

²

2000

Supercond. Sci. Technol.

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Copper oxide superconductors possess multi-layered structures with a layer sequence of -CuO2 -(Q-CuO2 )n -1 -AO-(MO1± )m -AO- or -CuO2 -B-(O2 -B)s -1 -CuO2 -AO-(MO1± )m -AO- along the elongated c axis. Based on this layer sequence, the known copper oxide structures are categorized as members of the homologous series, Mm Ar Qn -1 Cun Om +r +2n ± (M-mr (n -1)n ; category A) or Mm A2k Bs Cu1+k Om +4k +2s ± (M-m (2k )s (1+k ); category B). Stabilization of such structures especially in the case of high values of the n /s parameter, i.e. the higher members of the homologous series, has been demonstrated to be apparently promoted under high pressures and/or strongly oxidizing conditions. Consequently, techniques for applying both high oxygen gas pressures (10-2000 atm) and ultra-high solid-medium pressures (2-8 GPa) have been advantageously utilized in synthesizing various superconductive copper oxide phases. Especially the ultra-high solid-medium pressure synthesis carried out in the so-called cubic-anvil/belt-type apparatus has proven to be extremely successful in synthesizing novel superconductive phases. In order to achieve high partial pressures of oxygen in the solid-medium environment, `external' oxygen-generating oxides such as KClO4 , KClO3 and Ag2 O2 are commonly added to the precursor mixtures. It is emphasized that in some cases it is possible to utilize `internal' oxidizing agents alone, i.e. highly oxidized precursors such as BaCuO2+ and Ba2 Cu3 O5+ containing metal constituents common with the desired copper oxide phase only. In the present paper, the potential and applications of high-pressure techniques in synthesizing multi-layered copper oxides and related structures are reviewed and discussed with emphasis on the important `historical' discoveries of novel phases and the present status of controlled production of high-quality samples of such phases.

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Flux creep measurements in shocked YBa2Cu3O7 and La1.85Sr0.15CuO4

Cited by 8 publications

References 2 publications

Output Characteristics of Solar-Power-Driven Thermionic Energy Converter

Output Characteristics of Solar-Power-Driven Thermionic Energy Converter

Consolidation of Bi-Sr-Ca-Cu-O superconductors by the shock-loading method

Application of high-pressure techniques: stabilization and oxidation-state control of novel superconductive and related multi-layered copper oxides

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