TEM and critical current density studies of melt-textured YBa2Cu3Ox with silver and Y2BaCuO5 additions

Mironova, M.; Lee, D.F.; Saláma, K.

doi:10.1016/0921-4534(93)90741-8

Cited by 62 publications

(23 citation statements)

References 21 publications

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“…The presence of defects in superconducting grains or at the grain boundaries of MgB 2 leads to the J c enhancement of MgB 2 . The defects can be made artificially either through physical [6][7][8][9][10][11][12][13] or chemical [14][15][16] methods. Particle (neutron, electron or ion) irradiation is a well-known process that can form defects physically through the collision of accelerated particles to the targeting materials.…”

Section: Introductionmentioning

confidence: 99%

“…Particle (neutron, electron or ion) irradiation is a well-known process that can form defects physically through the collision of accelerated particles to the targeting materials. Small defects such as vacancies and cavities can be formed in the superconducting matrix through particle irradiation [15][16][17][18][19][20] . As a result of the defect formation, the J c at * Corresponding author: cjkim2@kaeri.re.kr the magnetic fields of the particle-irradiated MgB 2 was much higher than that of MgB 2 with no irradiation [21,22].…”

Section: Introductionmentioning

confidence: 99%

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Enhanced critical current density of in situ processed MgB₂ bulk superconductors with MgB₄ additions

S.H.Kim¹,

Kang²,

Jun³

et al. 2017

Progress in Superconductivity and Cryogenics

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The effects of MgB 4 addition on the superconducting properties and the microstructure of in situ processed MgB 2 bulk superconductors were studied. MgB 4 powder of 1-20 wt.% was mixed with (Mg + 2B) powder and then pressed into pellets. The pellets of (Mg + 2B + xMgB 4 ) were heat-treated at 650 ℃ for 1 h in flowing argon. The powder X-ray diffraction (XRD) analysis for the heat-treated samples showed that the major formed phase in all samples was MgB 2 and the minor phases were MgB 4 and MgO. The full width at half maximum (FWHM) values showed that the grain size of MgB 2 decreased as the amount of MgB 4 addition increased. MgB 4 particles included in a MgB 2 matrix is considered to suppress the grain growth of MgB 2 . The onset temperatures (T c,onset ) of MgB 2 with MgB 4 addition (0-10 wt.%) was between 37-38 K. The 20 wt.% MgB 4 addition slightly reduced the T c,onset of MgB 2 to 36.5 K. This result indicates that MgB 4 addition did not influence the superconducting transition temperature (T c ) of MgB 2 significantly. On the other hand, the small additions of 1-5 wt.% MgB 4 increased the critical current density (J c ) of MgB 2 . The J c enhancement by MgB 4 addition is attributed not only to the grain size refinement but also to the possible flux pinning of MgB 4 particles dispersed in a MgB 2 matrix.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Enhanced critical current density of in situ processed MgB₂ bulk superconductors with MgB₄ additions

S.H.Kim¹,

Kang²,

Jun³

et al. 2017

Progress in Superconductivity and Cryogenics

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“…It was found that the dislocation density increases near the interfaces with high surface curvature and between 211 particles with small interparticle spacing [10]. Enhancement in J~ has also been observed in mechanically deformed melt-textured 123, where the dislocation density within the bulk material was found to increase as a result of deformation [11,12].…”

Section: Introductionmentioning

confidence: 63%

“…Recent studies [9,10] have indicated that dislocations in the vicinity of the 123/211 interfaces may be an important factor in the enhancement in Jc. It was found that the dislocation density increases near the interfaces with high surface curvature and between 211 particles with small interparticle spacing [10].…”

Section: Introductionmentioning

confidence: 99%

Structure and defects at Y2BaCuO5 interfaces in melt-textured YBa2Cu3Ox superconductors

et al. 1994

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Y2BaCuO5 (211) inclusions are prominent microstructural features found in melt-textured YBa2Cu30~ (123) superconductors. These particles are of interest because the 123/211 interfaces and the interface-associated defects have been proposed to be flux pinning centers. In addition, the 211 particles are believed to be heterogeneous nucleation centers of dislocation which can increase the critical current density of 123. Unfortunately, only limited studies have been performed on these particles to ascertain their roles in flux pinning. In this investigation, 211 particles, the interfacial structure and defects in undeformed and mechanically deformed melt-textured 123 have been studied by transmission electron microscopy. It was found that there appears to be a preferred orientation between large oblong 211 particles and the 123 matrix. In addition, while the 123/211 interfaces in undeformed 123 are sharp and relatively undistorted, the interfaces in deformed 123 samples are much thicker. Also, the distribution of strained regions and dislocations around oblong 211 particles in undeformed 123 is nonuniform; the interfaces of low surface curvature are relatively free of defects while the surfaces of high curvature are abundant in dislocations. In contrast, the 123/211 interfaces in deformed 123 samples contain high density of dislocations regardless of interface curvature.

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“…Defects such as vacancy, dislocation, twins, stacking faults and non-superconducting lattice are developed during processing and oxygenation heat treatment [3][4][5][6][7][8]. They can effectively act as flux pinning sites which pin the flux in the superconducting matrix.…”

Section: Introductionmentioning

confidence: 99%

Effects of electron beam irradiation on the superconducting properties of YBCO thin films

Lee¹,

Choi²,

Jun³

et al. 2016

Progress in Superconductivity and Cryogenics

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The effects of electron beam (EB) irradiation on the superconducting critical temperature (T c ) and critical current density (J c ) of YBCO films were studied. The YBCO thin films were irradiated using a KAERI EB accelerator with an energy of 0.2 MeV and a dose of 10 15 -10 16 e/cm 2 . A small T c decrease and a broad superconducting transition were observed as the EB dose increased. The value of J c s (at 20 K, 50 K and 70 K) increased at doses of 7.5×10 15 and 2.2×10 16 e/cm 2 . However, J c s decreased as the dose increased further. The X-ray diffraction (XRD) analysis showed that the c axis of YBCO was elongated and the full width at half maximum (FWHM) increased as the dose increased, which is strong evidence of the atomic displacement by EB irradiation. The transmission electron microscopy (TEM) showed that the amorphous layer formed in the vicinity of the surfaces of the irradiated films. The amorphous phase was often present as an isolated form in the interior of the films. In addition to the formation of the amorphous phase, many striations running along the a-b direction of YBCO were observed. The high magnification lattice image showed that the striations were stacking faults. The enhancement of J c by EB irradiation is likely to be due to the lattice distortion and the formation of defects such as vacancies and stacking faults. The decrease in J c at a high EB dose is attributed to the extension of the amorphous region of a non-superconducting phase.

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TEM and critical current density studies of melt-textured YBa2Cu3Ox with silver and Y2BaCuO5 additions

Cited by 62 publications

References 21 publications

Enhanced critical current density of in situ processed MgB₂ bulk superconductors with MgB₄ additions

Enhanced critical current density of in situ processed MgB₂ bulk superconductors with MgB₄ additions

Structure and defects at Y2BaCuO5 interfaces in melt-textured YBa2Cu3Ox superconductors

Effects of electron beam irradiation on the superconducting properties of YBCO thin films

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TEM and critical current density studies of melt-textured YBa2Cu3Ox with silver and Y2BaCuO5 additions

Cited by 62 publications

References 21 publications

Enhanced critical current density of in situ processed MgB2 bulk superconductors with MgB4 additions

Enhanced critical current density of in situ processed MgB2 bulk superconductors with MgB4 additions

Structure and defects at Y2BaCuO5 interfaces in melt-textured YBa2Cu3Ox superconductors

Effects of electron beam irradiation on the superconducting properties of YBCO thin films

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Enhanced critical current density of in situ processed MgB₂ bulk superconductors with MgB₄ additions

Enhanced critical current density of in situ processed MgB₂ bulk superconductors with MgB₄ additions