Transmission electron microscope study on electrodeposited Gd2O3 and Gd2Zr2O7 buffer layers for YBa2Cu3O7−δ superconductors

Zhao, Wenjun; Norman, A. G.; Phok, Sovannary; Bhattacharya, R. N.

doi:10.1016/j.physc.2008.05.282

Cited by 11 publications

(7 citation statements)

References 13 publications

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“…16 Although the precursors, lms thicknesses and annealing procedures are the key factors in determining the texture quality of the CSD-buffer layer, there are seemingly no signicant microstructural differences among rare-earth zirconate layers, especially for the thick lms prepared by mono-coating routes. Similar sponge-like microstructures with high densities of nanovoids have been observed by several groups in the lm bodies as well as on the surfaces of the CSD buffer layers 14,[17][18][19][20] despite the use of varying materials, solution synthetic routes and heat treatment processes. To date, no direct evidence has been found to explain the formation of such structural features.…”

Section: Resultssupporting

confidence: 72%

Study on advanced Ce_0.9La_0.1O₂/Gd₂Zr₂O₇ buffer layers architecture towards all chemical solution processed coated conductors

Zhao

et al. 2015

J. Mater. Chem. A

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Chemical solution deposition is a versatile technique to deposit functional oxide films with low cost. In this study, this approach was employed to grow multi-layered, second-generation, high-temperature superconductors ("coated conductors") with high superconducting properties. The Ce 0.9 La 0.1 O 2 / Gd 2 Zr 2 O 7 buffer layer stack and the 200 nm thick YBa 2 Cu 3 O 7 (YBCO) superconducting layer were sequentially deposited on textured NiW substrates using metal-organic deposition routes. The surface texture of the Gd 2 Zr 2 O 7 barrier layer deteriorates when the film thickness increases to 80 nm, although the global texture retains a sharp biaxial orientation, as determined by conventional X-ray diffraction. We paid particular attention to improving the surface quality in terms of crystallographic orientation and local flatness after depositing a Ce 0.9 La 0.1 O 2 thin film as a cap layer. From a comprehensive analysis of the surface morphology and misorientation maps constructed by electron backscattering diffraction, it is found that these improvements are mainly attributed to: (i) the preferential nucleation of Ce 0.9 La 0.1 O 2 crystals on the Gd 2 Zr 2 O 7 grains with desirable orientations; and (ii) the predominant two-dimensional growth of the Ce 0.9 La 0.1 O 2 crystals in the layer. Moreover, the microstructure and superconducting performance of the YBCO superconducting layer were thoroughly characterized and compared with those of films deposited on single-crystal substrates using the same technique. A promising critical current density of 2.2 MA cm À2 (77 K, self-field) was achieved on such an all chemical derived configuration, demonstrating the high quality of the buffer layer stack and the feasibility of using all chemical solution routes for the fabrication of low-cost coated conductors.

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Section: Resultssupporting

confidence: 72%

Study on advanced Ce_0.9La_0.1O₂/Gd₂Zr₂O₇ buffer layers architecture towards all chemical solution processed coated conductors

Zhao

et al. 2015

J. Mater. Chem. A

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“…3 for a sample before the oxidation treatment. The LZO grains, well visible from top, have size in the range of 20-50 This phenomenon has already been observed several times by others [12]- [14] and curiously does not impede the development of ahigh quality textured layer (in-plane 7.5 , out of plane 6-10 depending whether the measurement was done along rolling direction, RD, or along transverse one, TD). Up to now, the origin of the pores is unclear but is probably associated with the gas emitted during the pyrolysis step.…”

Section: B Microstructuresupporting

confidence: 58%

LZO, a Protective Barrier Against Oxidation of NiW Alloys

Petit

Mikolajczyk

Soubeyroux

et al. 2011

IEEE Trans. Appl. Supercond.

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International audienceLow cost Coated Conductors (CC) are required to access competitive superconducting cables. The buffer layer architecture is a key aspect of CC processing and very efficient results have been obtained with complex architecture. However, it may not be useful to have so high Jc for cable applications, and then simpler architectures have been considered. Our group has suggested in 2008 that only one buffer could be sufficient. As the deposition of YBCO needs an oxygenated atmosphere at rather high temperature, it is a key stage to study the oxygenation'seffects on the buffer layer. The aim of this study is to show results of annealing La(2)Zr(2)O(7)/NiW substrates (LZO/NiW), with LZO deposited by MOD, under different oxygen atmospheres and conditions closed to those used in MOCVDYBCO deposition. The microstructure of the buffer layer is studied in details and tentatively related to oxidation behavior. It is shown in addition that the substrate plays in fact a crucial role, grain boundaries being the main source of oxidation. We anticipate that perhaps oxidation is an important source of degradation of critical current in YBCO

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“…The fact that we obtain similar results independent of the segmentation method indicates that these measurements can be regarded as reliable. Reference reported nanovoid densities in similar solution derived pyrochlore thin films measured from plan-view TEM images; however, quantification is difficult since information is taken from 2D images. Nanovoid density quantification is improved by electron tomography since the volume of the sample is probed, allowing a true 3D characterization.…”

Section: Resultsmentioning

confidence: 99%

Measuring Porosity at the Nanoscale by Quantitative Electron Tomography

et al. 2010

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Quantitative electron tomography is proposed to characterize porous materials at a nanoscale. To achieve reliable three-dimensional (3D) quantitative information, the influence of missing wedge artifacts and segmentation methods is investigated. We are presenting the "Discrete Algebraic Reconstruction Algorithm" as the most adequate tomography method to measure porosity at the nanoscale. It provides accurate 3D quantitative information, regardless the presence of a missing wedge. As an example, we applied our approach to nanovoids in La2Zr2O7 thin films.

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Transmission electron microscope study on electrodeposited Gd2O3 and Gd2Zr2O7 buffer layers for YBa2Cu3O7−δ superconductors

Cited by 11 publications

References 13 publications

Study on advanced Ce_0.9La_0.1O₂/Gd₂Zr₂O₇ buffer layers architecture towards all chemical solution processed coated conductors

Study on advanced Ce_0.9La_0.1O₂/Gd₂Zr₂O₇ buffer layers architecture towards all chemical solution processed coated conductors

LZO, a Protective Barrier Against Oxidation of NiW Alloys

Measuring Porosity at the Nanoscale by Quantitative Electron Tomography

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Transmission electron microscope study on electrodeposited Gd2O3 and Gd2Zr2O7 buffer layers for YBa2Cu3O7−δ superconductors

Cited by 11 publications

References 13 publications

Study on advanced Ce0.9La0.1O2/Gd2Zr2O7 buffer layers architecture towards all chemical solution processed coated conductors

Study on advanced Ce0.9La0.1O2/Gd2Zr2O7 buffer layers architecture towards all chemical solution processed coated conductors

LZO, a Protective Barrier Against Oxidation of NiW Alloys

Measuring Porosity at the Nanoscale by Quantitative Electron Tomography

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Study on advanced Ce_0.9La_0.1O₂/Gd₂Zr₂O₇ buffer layers architecture towards all chemical solution processed coated conductors

Study on advanced Ce_0.9La_0.1O₂/Gd₂Zr₂O₇ buffer layers architecture towards all chemical solution processed coated conductors