Dynamic behavior of reversible oxygen migration in irradiated-annealed high temperature superconducting wires

Abstract We use atomically resolved scanning transmission electron microscopy and electron energy loss spectroscopy to determine the atomic-scale structural, chemical and electronic properties of artificial engineered defects in irradiated-annealed high temperature superconducting wires based on epitaxial Y(Dy)BCO film. We directly probe the oxygen vacancy defects in both plane and chain sites after irradiation with 18-meV Au ions. The plane site vacancies are reoccupied during post-annealing treatment. Our results demonstrate the dynamic reversible behavior of oxygen point defects, which explains the depression and recovery of self-field critical current and critical temperature in irradiation-annealing process. These findings reveal the strong effect of oxygen vacancies in different sites on the superconductivity properties of irradiated Y(Dy)BCO film, and provide important insights into defects engineering of 2G HTS coil wires.

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Analysis of Nanometer Sized Pyrogenic Particles by Scanning Transmission Electron Microscopy

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s042482010013746x ◽

1995 ◽

Vol 53 ◽

pp. 218-219

Author(s):

DJ Wallis ◽

ND Browning ◽

CM Megaridis

Keyword(s):

Operating Conditions ◽

Atomic Scale ◽

Contrast Imaging ◽

Chemical Mechanisms ◽

Transmission Electron ◽

Angle Scattering ◽

Scanning Transmission ◽

Z Contrast ◽

Physical And Chemical ◽

Electron Energy Loss

Iron is a ubiquitous element on the earth's surface, and is thus involved in most naturally occurring fires. Iron organometalic compounds have also been known to suppress carbonaceous soot emissions under certain operating conditions of practical combustors. In order to unravel the physical and chemical mechanisms of influence, of iron on the emission of carbonaceous pyrogenic particles, finescale characterization techniques need to be implemented.The combined techniques of Z-contrast imaging and electron energy loss spectroscopy (EELS) in a VG HB-501 dedicated STEM are ideally suited to study such a system. The sensitivity of the Z-contrast imaging technique to high-Z materials makes it ideal for location of the iron particles within the much lower atomic number matrix. As only the high-angle scattering is used in the image formation, EELS can be performed simultaneously from a position defined in the image. This accurate positioning of the probe by the Z-contrast image permits both compositional and bonding information to be obtained with a spatial resolution approaching the atomic scale.

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Atomic Scale Imaging and Energy Loss Spectroscopy of Epitaxial Graphene

MRS Proceedings ◽

10.1557/opl.2014.845 ◽

2014 ◽

Vol 1714 ◽

Author(s):

Giuseppe Nicotra ◽

Quentin M. Ramasse ◽

Mario Scuderi ◽

Paolo Longo ◽

Ioannis Deretzis ◽

...

Keyword(s):

Electron Microscopy ◽

Transmission Electron Microscopy ◽

Energy Loss ◽

Electron Energy Loss Spectroscopy ◽

Scanning Transmission Electron Microscopy ◽

Amorphous Film ◽

Atomic Scale ◽

Transmission Electron ◽

Scanning Transmission ◽

Electron Energy Loss

ABSTRACTAtomic-resolution structural and spectroscopic characterization techniques (scanning transmission electron microscopy and electron energy loss spectroscopy) are combined with nanoscale electrical measurements (conductive atomic force microscopy) to study at the atomic scale the properties of graphene grown epitaxially through the controlled graphitisation of Si-face and C-face hexagonal SiC(0001) substrates by high temperature annealing. A scanning transmission electron microscopy analysis, carried out at 60KeV of beam energy, below the knock-on threshold for carbon to ensure no damage is imparted to the film by the electron beam, demonstrates that the buffer layer present on the planar SiC(0001) Si-face delaminates from it on the (11-2n) facets of SiC surface steps, In addition, electron energy loss spectroscopy reveals that the delaminated layer has a similar electronic configuration to purely sp2-hybridized graphene. A thin amorphous film is found on the C-face, instead, which strongly suppresses epitaxy with the SiC substrate. Structurally, the amorphous area is inhomgeneous, as its Si-concentration gradually decreases while approaching the first graphene layer, which is purely sp2-hybridized. Based on these features, we discuss differences and similarities between the C-only buffer layer that forms on the Si-face of SiC with respect to the thicker C/Si amorphous film of the C-face.

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Local crystallographic shear structures in a[201] extended mixed dislocations of SrTiO3 unraveled by atomic-scale imaging using transmission electron microscopy and spectroscopy

Faraday Discussions ◽

10.1039/c8fd00102b ◽

2019 ◽

Vol 213 ◽

pp. 245-258 ◽

Cited By ~ 1

Author(s):

Hongchu Du ◽

Chun-Lin Jia ◽

Joachim Mayer

Keyword(s):

Electron Microscopy ◽

Transmission Electron Microscopy ◽

Scanning Transmission Electron Microscopy ◽

Atomic Scale ◽

X Ray ◽

Shear Structures ◽

Transmission Electron ◽

Scanning Transmission ◽

Crystallographic Shear ◽

Electron Energy Loss

Atomic details of extended mixed dislocations in a SrTiO3 bicrystal are studied using scanning transmission electron microscopy, electron energy loss spectroscopy, and energy dispersive X-ray spectroscopy techniques.

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Electron Microscopy Studies of The Chemistry And Microstructure of BaF2 / YBa2Cu3O7-x Thin Films

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100171717 ◽

1994 ◽

Vol 52 ◽

pp. 796-797

Author(s):

J. L. Lee ◽

C. A. Weiss ◽

R. A. Buhrman ◽

J. Silcox

Keyword(s):

Thin Film ◽

Electron Microscopy ◽

Thin Films ◽

Scanning Transmission Electron Microscope ◽

Atomic Scale ◽

Island Growth ◽

Multilayer Systems ◽

Transmission Electron ◽

Scanning Transmission ◽

Mgo Substrate

BaF2 thin films are being investigated as candidates for use in YBa2Cu3O7-x (YBCO) / BaF2 thin film multilayer systems, given the favorable dielectric properties of BaF2. In this study, the microstructural and chemical compatibility of BaF2 thin films with YBCO thin films is examined using transmission electron microscopy and microanalysis. The specimen was prepared by using laser ablation to first deposit an approximately 2500 Å thick (0 0 1) YBCO thin film onto a (0 0 1) MgO substrate. An approximately 7500 Å thick (0 0 1) BaF2 thin film was subsequendy thermally evaporated onto the YBCO film.Images from a VG HB501A UHV scanning transmission electron microscope (STEM) operating at 100 kV show that the thickness of the BaF2 film is rather uniform, with the BaF2/YBCO interface being quite flat. Relatively few intrinsic defects, such as hillocks and depressions, were evident in the BaF2 film. Moreover, the hillocks and depressions appear to be faceted along {111} planes, suggesting that the surface is smooth and well-ordered on an atomic scale and that an island growth mechanism is involved in the evolution of the BaF2 film.

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High Spatial Resolution Compositional Analysis at Interfaces

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s1431927600001513 ◽

1980 ◽

Vol 38 ◽

pp. 356-359

Author(s):

John B. Vander Sande ◽

Thomas F. Kelly ◽

Douglas Imeson

Keyword(s):

Electron Microscope ◽

High Spatial Resolution ◽

Compositional Analysis ◽

Scanning Transmission Electron Microscope ◽

Thin Specimen ◽

X Ray ◽

Volume Of Interest ◽

Transmission Electron ◽

Scanning Transmission ◽

Electron Energy Loss

In the scanning transmission electron microscope (STEM) a fine probe of electrons is scanned across the thin specimen, or the probe is stationarily placed on a volume of interest, and various products of the electron-specimen interaction are then collected and used for image formation or microanalysis. The microanalysis modes usually employed in STEM include, but are not restricted to, energy dispersive X-ray analysis, electron energy loss spectroscopy, and microdiffraction.

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Chemical Quantification of Atomic-Scale EDS Maps under Thin Specimen Conditions

Microscopy and Microanalysis ◽

10.1017/s1431927614013245 ◽

2014 ◽

Vol 20 (6) ◽

pp. 1782-1790 ◽

Cited By ~ 26

Author(s):

Ping Lu ◽

Eric Romero ◽

Shinbuhm Lee ◽

Judith L. MacManus-Driscoll ◽

Quanxi Jia

Keyword(s):

Atomic Scale ◽

Specimen Thickness ◽

Peak Width ◽

Thin Specimen ◽

Gaussian Peak ◽

X Ray ◽

Transmission Electron ◽

Scanning Transmission ◽

The Relationship ◽

Chemical Quantification

AbstractWe report our effort to quantify atomic-scale chemical maps obtained by collecting energy-dispersive X-ray spectra (EDS) using scanning transmission electron microscopy (STEM) (STEM-EDS). With thin specimen conditions and localized EDS scattering potential, the X-ray counts from atomic columns can be properly counted by fitting Gaussian peaks at the atomic columns, and can then be used for site-by-site chemical quantification. The effects of specimen thickness and X-ray energy on the Gaussian peak width are investigated using SrTiO3 (STO) as a model specimen. The relationship between the peak width and spatial resolution of an EDS map is also studied. Furthermore, the method developed by this work is applied to study cation occupancy in a Sm-doped STO thin film and antiphase boundaries (APBs) present within the STO film. We find that Sm atoms occupy both Sr and Ti sites but preferably the Sr sites, and Sm atoms are relatively depleted at the APBs likely owing to the effect of strain.

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Atomic-scale structural and compositional analyses of Ruddlesden-Popper planar faults in AO-excess SrTiO3 (A = Sr2+, Ca2+, Ba2+) ceramics

Journal of Materials Research ◽

10.1557/jmr.2009.0321 ◽

2009 ◽

Vol 24 (8) ◽

pp. 2596-2604 ◽

Cited By ~ 8

Author(s):

Sašo Šturm ◽

Makoto Shiojiri ◽

Miran Čeh

Keyword(s):

Electron Microscopy ◽

Transmission Electron Microscopy ◽

Dark Field ◽

Atomic Scale ◽

Transmission Electron ◽

Initial Stage ◽

Final Microstructure ◽

Scanning Transmission ◽

The Matrix ◽

Annular Dark Field

The microstructure in AO-excess SrTiO3 (A = Sr2+, Ca2+, Ba2+) ceramics is strongly affected by the formation of Ruddlesden-Popper fault–rich (RP fault) lamellae, which are coherently intergrown with the matrix of the perovskite grains. We studied the structure and chemistry of RP faults by applying quantitative high-resolution transmission electron microscopy and high-angle annular dark-field scanning transmission electron microscopy analyses. We showed that the Sr2+ and Ca2+ dopant ions form RP faults during the initial stage of sintering. The final microstructure showed preferentially grown RP fault lamellae embedded in the central part of the anisotropic perovskite grains. In contrast, the dopant Ba2+ ions preferably substituted for Sr2+ in the SrTiO3 matrix by forming a BaxSr1−xTiO3 solid solution. The surplus of Sr2+ ions was compensated structurally in the later stages of sintering by the formation of SrO-rich RP faults. The resulting microstructure showed RP fault lamellae located at the surface of equiaxed BaxSr1-xTiO3 perovskite grains.

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