Transmission electron microscopic and critical current density investigations of decomposed YBa2Cu4O8

Previous work on YBa2Cu3O7−x (YBCO) + BaSnO3 (BSO) films with a single composition showed significant critical current density (Jc) improvements at higher fields but lowered Jc in low fields. A detailed study on BSO concentrations provided here demonstrates that significant Jc enhancement can occur even up to 20 mol% BSO inclusion, where typical particulate inclusions in these concentrations degrade the YBCO performance. YBCO + BSO films were processed on (100) LaAlO3 substrates using premixed targets of YBa2Cu3O7-x (YBCO) with additions of 2, 4, 10, and 20 mol% BSO. The critical transition temperature Tc of the films remained high (>87 K), even with large amounts (20 mol%) of BSO. YBCO + BSO films showed a gradual increase in Jc at high fields as the amount of BSO was increased. More than an order of magnitude increase in Jc was measured in YBCO + BSO samples as compared to regular YBCO at 4 T. YBCO + 10 mol% BSO films showed overall improvement at all the field ranges while YBCO + 20 mol% BSO was better only at high fields. Transmission electron microscopy revealed the presence of ∼7–8-nm-diameter BSO nanocolumns, the density of which increased with increasing BSO content correlating well with the observed improvements in Jc.

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Spatial variations in composition in high-critical-current-density Bi-2223 tapes

Journal of Materials Research ◽

10.1557/jmr.2000.0047 ◽

2000 ◽

Vol 15 (2) ◽

pp. 285-295 ◽

Cited By ~ 12

Author(s):

T. G. Holesinger ◽

J. F. Bingert ◽

M. Teplitsky ◽

Q. Li ◽

R. Parrella ◽

...

Keyword(s):

Critical Current Density ◽

Critical Current ◽

Current Density ◽

Compositional Analysis ◽

Structural Features ◽

Spatial Variations ◽

High Critical Current Density ◽

Transmission Electron ◽

Filament Structure ◽

Considerable Range

A detailed compositional analysis of high-critical-current-density (Jc) (55 and 65 kA/cm2at 77 K) (Bi,Pb)2Sr2Ca2Cu3Oy(Bi-2223) tapes was undertaken by energy dispersive spectroscopy in the transmission electron microscope. Structural features were coupled with characteristic compositions of the Bi-2223 phase. The average of all compositional measurements of the Bi-2223 phase was determined to be Bi1.88Pb0.23Sr1.96Ca1.95Cu2.98Oy. However, spatial variations in the Bi-2223 composition and differing phase equilibria were found throughout the filament structure. In particular, a considerable range of Bi-2223 compositions can be found within a single tape, and the lead content of the Bi-2223 phase is significantly depressed in the vicinity of lead-rich phases. The depletion of lead in the Bi-2223 phase around the 3221 phases may be a current-limiting microstructure in these tapes.

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Critical Current Density and Microstructure of Yba2Cu3O7-X Films as a Function of Film Thickness

MRS Proceedings ◽

10.1557/proc-169-703 ◽

1989 ◽

Vol 169 ◽

Cited By ~ 3

Author(s):

A. Mogro-Campero ◽

L.G. Turner ◽

E.L. Hall ◽

N. Lewis

Keyword(s):

Critical Current Density ◽

Critical Current ◽

Current Density ◽

Film Plane ◽

Nominal Composition ◽

Substrate Plane ◽

Furnace Annealing ◽

Cross Sectional ◽

Continuous Layer ◽

Transmission Electron

AbstractThin films of nominal composition YBa2Cu3O7‐x (YBCO) were produced on (100) SrTiO3 substrates by coevaporation and furnace annealing. Film thicknesses in the range of 0.2 to 2.4/μm were analyzed. Microstructural investigations by cross sectional transmission electron microscopy (TEM) reveal a continuous layer of about 0.4 μm thickness adjacent to the substrate with c‐axis normal to the substrate plane. In thicker films the remaining top portion has the c‐axis in the film plane. The critical current density (J ) at 77 K decreases with increasing thickness in the thickness range exceeding 0.4 μm, qualitatively consistent with the microstructural observations, but quantitatively inconsistent with a simple model based on the microstructural data.

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EFFECT OF NANO-Y-ZrO2 ADDITION ON THE MICROSTRUCTURE AND CRITICAL CURRENT DENSITY OF MgB2 SUPERCONDUCTORS

International Journal of Nanoscience ◽

10.1142/s0219581x04002383 ◽

2004 ◽

Vol 03 (04n05) ◽

pp. 563-569 ◽

Cited By ~ 1

Author(s):

Q. W. YAO ◽

X. L. WANG ◽

A. H. LI ◽

S. X. DOU ◽

P. R. MUNROE

Keyword(s):

Critical Current Density ◽

Critical Current ◽

Current Density ◽

Magnetic Measurements ◽

Transmission Electron ◽

Long Time ◽

Powder Addition ◽

Short Time ◽

Mgb2 Superconductors

Polycrystalline MgB 2 samples with 0, 5, 10, and 20 wt% nano- Y - ZrO 2 (YSZ) powder addition were prepared by short time, as little as several minutes, or long time in-situ reaction process. The phases, microstructures and flux pinning behaviors were characterized using X-ray diffractometry (XRD), Scanning Electron Microscopy (SEM), Transmission Electron Microscope (TEM) and Magnetic Measurements. Results indicated that nano-YSZ particles included in MgB 2 grains. Samples doped with 10wt% YSZ powders showed new record of critical current density Jc as high as 1×106 and 4×106 A/cm 2 in low magnetic fields at 30 and 20K, respectively. However, the Jc drops faster compared to that made by long time sintering samples. It is proposed that the improved Jc in low fields was due to the enhanced density of the sample, which was caused by the YSZ nano-particle inclusion.

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Magnetic Field Dependence of Critical Current Density of PLD RE-Ba-Cu-O (RE=Gd, Sm, Dy, Er, Y) Film on CeO2 Capped IBAD-GZO Layers

MRS Proceedings ◽

10.1557/proc-868-c8.10 ◽

2005 ◽

Vol 868 ◽

Author(s):

Kazuhiro Takahashi ◽

Masaya Konishi ◽

Akira Ibi ◽

Tomonori Watanabe ◽

Takemi Muroga ◽

...

Keyword(s):

Magnetic Fields ◽

Critical Current Density ◽

Critical Current ◽

Current Density ◽

Ion Beam ◽

Stacking Faults ◽

Coated Conductors ◽

Weak Anisotropy ◽

Ion Beam Assisted Deposition ◽

Transmission Electron

AbstractWe prepared REBa2Cu3O7- δ (RE= Gd, Sm, Dy, Er, Y) coated conductors on pulsed laser deposition (PLD) -CeO2/ion-beam assisted deposition (IBAD) – Gd2Zr2O7 (GZO) / metal tapes by the PLD method and measured the characteristics in magnetic fields. The GdBa2Cu3O7- σ (Gd-123) films showed superior characteristics than others in magnetic fields and showed weak anisotropy. Critical current density (Jc) value of the Gd-123 film was 3.87MA/cm2 at self-field and 0.19MA/cm2 at 3 T of perpendicular field to the tape surface in liquid nitrogen (77 K). Angular dependences in magnetic fields (Jc -Θ) of the Gd-123 and the SmBa2Cu3O7- σ (Sm-123) were superior to others and peaks in Jc -Θ were found also at 0 degree. The reduction ratios of Jc in Jc -Θ for the Gd-123 film and the Sm-123 film were smaller than other films. Transmission electron microscopy showed that the Gd-123 film had many stacking faults. It may be considered that this stacking faults naturally introduced by the PLD method contribute to improvement of anisotropy of Jc -Θ in the Gd-123 film.

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Microstructural characterization of YBa2Cu3O7-x thin films formed by metalorganic CVD

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100089718 ◽

1991 ◽

Vol 49 ◽

pp. 1080-1081

Author(s):

P. Lu ◽

W. Huang ◽

C.S. Chern ◽

Y.Q. Li ◽

J. Zhao ◽

...

Keyword(s):

Thin Film ◽

Thin Films ◽

Critical Current Density ◽

Critical Current ◽

Current Density ◽

Film Growth ◽

Chemical Vapor ◽

Microstructural Characterization ◽

Ion Milling ◽

Conventional Grinding

The YBa2Cu3O7-x thin films formed by metalorganic chemical vapor deposition(MOCVD) have been reported to have excellent superconducting properties including a sharp zero resistance transition temperature (Tc) of 89 K and a high critical current density of 2.3x106 A/cm2 or higher. The origin of the high critical current in the thin film compared to bulk materials is attributed to its structural properties such as orientation, grain boundaries and defects on the scale of the coherent length. In this report, we present microstructural aspects of the thin films deposited on the (100) LaAlO3 substrate, which process the highest critical current density.Details of the thin film growth process have been reported elsewhere. The thin films were examined in both planar and cross-section view by electron microscopy. TEM sample preparation was carried out using conventional grinding, dimpling and ion milling techniques. Special care was taken to avoid exposure of the thin films to water during the preparation processes.

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The blister of porphyria cutanea tarda: A Scanning and Transmission Electron Microscopic study

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100143298 ◽

1986 ◽

Vol 44 ◽

pp. 334-335

Author(s):

Veronika Burmeister ◽

R. Swaminathan

Keyword(s):

Electron Microscopy ◽

Transmission Electron Microscopy ◽

Basement Membrane ◽

Middle Age ◽

Porphyria Cutanea Tarda ◽

Minor Trauma ◽

Electron Microscopic ◽

Transmission Electron Microscopic Study ◽

Transmission Electron ◽

Transmission Electron Microscopic

Porphyria cutanea tarda (PCT) is a disorder of porphyrin metabolism which occurs most often during middle age. The disease is characterized by excessive production of uroporphyrin which causes photosensitivity and skin eruptions on hands and arms, due to minor trauma and exposure to sunlight. The pathology of the blister is well known, being subepidermal with epidermodermal separation, it is not always absolutely clear, whether the basal lamina is attached to the epidermis or the dermis. The purpose of our investigation was to study the attachment of the basement membrane in the blister by comparing scanning with transmission electron microscopy.

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Facet Topography and Dislocation Structure as a Possible Source for Electrical Heterogeneity in [001] TILT Bicrystals of YBa2Cu3O7-δ

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100164155 ◽

1996 ◽

Vol 54 ◽

pp. 338-339

Author(s):

I-Fei Tsu ◽

D.L. Kaiser ◽

S.E. Babcock

Keyword(s):

Grain Boundary ◽

Critical Current Density ◽

Critical Current ◽

Current Density ◽

Electromagnetic Properties ◽

Length Scale ◽

Density Values ◽

Current Densities ◽

Applied Fields ◽

A Current

A current theme in the study of the critical current density behavior of YBa2Cu3O7-δ (YBCO) grain boundaries is that their electromagnetic properties are heterogeneous on various length scales ranging from 10s of microns to ˜ 1 Å. Recently, combined electromagnetic and TEM studies on four flux-grown bicrystals have demonstrated a direct correlation between the length scale of the boundaries’ saw-tooth facet configurations and the apparent length scale of the electrical heterogeneity. In that work, enhanced critical current densities are observed at applied fields where the facet period is commensurate with the spacing of the Abrikosov flux vortices which must be pinned if higher critical current density values are recorded. To understand the microstructural origin of the flux pinning, the grain boundary topography and grain boundary dislocation (GBD) network structure of [001] tilt YBCO bicrystals were studied by TEM and HRTEM.

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TEM comparison of osmium vs osmium with potassium ferricyanide secondary fixatives and the impact of secondary fixative temperature on tissue preservation/contrast quality

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100167019 ◽

1996 ◽

Vol 54 ◽

pp. 910-911

Author(s):

J. W. Horn ◽

B. J. Dovey-Hartman ◽

V. P. Meador

Keyword(s):

Osmium Tetroxide ◽

Potassium Ferricyanide ◽

Electron Microscopic ◽

Transmission Electron ◽

Microscopic Evaluation ◽

Cacodylate Buffer ◽

Transmission Electron Microscopic ◽

Glutaraldehyde Solution ◽

Temperature Impact ◽

The Impact

Osmium tetroxide (OsO4) is a universally used secondary fixative for routine transmission electron microscopic evaluation of biological specimens. Use of OsO4 results in good ultrastructural preservation and electron density but several factors, such as concentration, length of exposure, and temperature, impact overall results. Potassium ferricyanide, an additive used primarily in combination with OsO4, has mainly been used to enhance the contrast of lipids, glycogen, cell membranes, and membranous organelles. The purpose of this project was to compare the secondary fixative solutions, OsO4 vs. OsO4 with potassium ferricyanide, and secondary fixative temperature for determining which combination gives optimal ultrastructural fixation and enhanced organelle staining/contrast.Fresh rat liver samples were diced to ∼1 mm3 blocks, placed into porous processing capsules/baskets, preserved in buffered 2% formaldehyde/2.5% glutaraldehyde solution, and rinsed with 0.12 M cacodylate buffer (pH 7.2). Tissue processing capsules were separated (3 capsules/secondary fixative.solution) and secondarily fixed (table) for 90 minutes. Tissues were buffer rinsed, dehydrated with ascending concentrations of ethanol solutions, infiltrated, and embedded in epoxy resin.

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