Critical current density and related microstructures of TFA-MOD YBCO coated conductors

Yamada, Yutaka; Kim, Seokbeom; Araki, Takao; Takahashi, Yasuo; Yuasa, Toyotaka; Kurosaki, Haruhiko; Hirabayashi, I.; Iijima, Y.; Takeda, Kazuyuki

doi:10.1016/s0921-4534(01)00471-3

Cited by 16 publications

(12 citation statements)

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“…14 This I c performance level will most likely be obtained only through thick films (ജ1 m) of YBCO where the critical current density (J c ) of the YBCO films is in excess of 1 MA/cm 2 at liquid-nitrogen temperatures and self-field. Examples of some processes that can meet these requirements are ex situ conversion of YBCO precursors, [15][16][17][18][19][20][21][22][23] metalorganic chemical vapor deposition (MOCVD), 24,25 and physical vapor deposition (PVD) from mixed oxide targets or elemental sources in a suitable oxidizing vacuum environment. [26][27][28][29][30][31] The ex situ conversion of BaF 2 -based YBa 2 Cu 3 O y precursors is an economically attractive process for adding the superconducting layer to a coated conductor substrate.…”

Section: Introductionmentioning

confidence: 99%

“…15 Both processes have the capacity for producing high critical current density (J c ) YBCO films at high conversion rates. 9,[19][20][21]23,33 The conversion processes for the MOD-BaF 2 and PVD-BaF 2 precursor films share many key features after the pyrolysis step that converts the MOD-BaF 2 TFA-based precursors into the mixed metal oxyfluorides. 15,34 Areas of particular interest in the processing of BaF 2 -based YBCO films are nucleation and growth 16,18,35,36 in the presence of transient liquid phases, 16,18,35 rate limiting mechanisms, 37,38 oxygen partial pressures during processing, 16,17 through thickness J c uniformity, 39 and residual porosity in ex situ films.…”

Section: Introductionmentioning

confidence: 99%

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Liquid mediated growth and the bimodal microstructure of YBa₂Cu₃O_7−δ films made by the ex situ conversion of physical vapor deposited BaF₂ precursors

et al. 2005

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YBa 2 Cu 3 O y (YBCO) films produced by the ex situ conversion of BaF 2 -based precursors deposited by physical vapor deposition on ion-beam assisted deposited (IBAD) yttrium-stabilized zirconia (YSZ) and rolling-assisted biaxially textured substrates (RABiTS) templates are characterized by a bi-axially aligned, laminar grain structure that results from the anisotropic growth characteristics of the YBCO phase and its precipitation from a transient liquid phase during the conversion process. A bimodal microstructure characterizes these films and is defined by large, well-formed YBCO grains with Y 2 O 3 precipitates in the bottom region of the film and small YBCO grains with a high density of stacking faults in the upper half. Ba 2 Cu 3 O y or Ba-O-F/CuO second phase layers were often found between large YBCO grains in the bottom half of the films. YBCO grain sizes exceeded 50 m within the plane of the film in some cases. Conversely, discrete secondary phases of be found among the much smaller YBCO grains in the top portion of the bimodal structure. The dividing line of the bimodal structure was generally at one half of the film thickness, although exceptions to this trend were found. The highest critical current densities (J c ) and best film alignments for a given film thickness were found in samples where the layers of Ba 2 Cu 3 O y or Ba-O-F were minimized or eliminated from the films. Samples quenched after partial conversion show the segregation of CuO to the top region of the film and the lateral growth of large YBCO grains from a precursor mix of Y 2 Cu 2 O 5 and Ba-O-F. The data demonstrate that transient liquid phases are part of the conversion process of BaF 2 -based YBCO films. The control of both CuO segregation and the amount of liquid phases generated during the initial stages of phase formation is needed for optimizing the ex situ conversion process for high-J c coated conductors.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Liquid mediated growth and the bimodal microstructure of YBa₂Cu₃O_7−δ films made by the ex situ conversion of physical vapor deposited BaF₂ precursors

et al. 2005

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“…High-J c REBCO films over several MA/cm 2 have reportedly been successfully prepared by the so-called BaF 2 process. 4,5 High J c values of 4.5 MA/cm 2 were also reported for REBCO films prepared using the MOD process with fluorine-free acetylacetonate coating solutions. 16 The relatively low J c value of the 2-EH films in the present work was likely due to the numerous precipitates between the grains on the surface.…”

Section: Resultsmentioning

confidence: 79%

“…REBCO films with high J c values have been studied using the MOD technique with trifluoroacetate (TFA) coating solutions. 4,5 MOD employing fluorine-free solutions has the advantages of a simpler process and a shorter heating process than TFA-MOD, because removal of fluorine from the films unnecessary. [6][7][8] We previously reported that the reproducibility of high-T c and surface flatness of GdBa 2 Cu 3 O y (GdBCO) films was improved by using fluorine-free complex solutions.…”

Section: Introductionmentioning

confidence: 99%

INFLUENCE OF COATING SOLUTION COMPOSITION ON REBa₂Cu₃O_y (RE=Gd AND Sm, Eu, Gd) FILMS FABRICATED BY FLUORINE-FREE METAL–ORGANIC DEPOSITION

et al. 2010

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GdBa 2 Cu 3 O y ( GdBCO ) and Sm 0.33 Eu 0.33 Gd 0.33 Ba 2 Cu 3 O y ( SEG ) films were prepared by metal–organic deposition (MOD) using two fluorine-free solutions: a metal 2-ethylhexanate (2-EH) and a complex solution (CS) consisting of metal 2-EH and metal-naphthenate. We investigated the effects of these new fluorine-free solutions, and their potential use in the fabrication of several REBCO ( RE : rare earth) materials. The crystal growth, surface morphology, and superconducting properties of films prepared on single-crystal LaAlO 3 substrates at low oxygen partial pressure strongly depended upon the coating solution used. Films prepared using 2-EH exhibited improved thermal stability of the superconducting phase during heat treatment. On the other hand, films prepared by CS had a flat superconducting matrix, with a roughness of several tens of nm and large precipitates 2–3 μm in diameter. In addition, the CS films had a higher critical temperature (91.2 K) than the 2-EH film. The zero-field critical current density at 77.3 K was 0.19 MA/cm2 for 2-EH films, and 0.61 MA/cm2 for CS films.

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“…Yamada et al 400 used PLD-IBAD to deposit YSZ and CeO 2 buffer layers on short, non-textured Hastelloy substrates, and a solution approach, MOD, for the Y-123 layer. The J c result for this sample was 1.7 MA cm Ϫ2 .…”

Section: Results On Non-textured Polycrystalline Substratesmentioning

confidence: 99%

9 Developments in high temperature superconductivity

Silver

Pan

Ionescu

et al. 2002

Annu. Rep. Prog. Chem., Sect. C: Phys. Chem.

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Critical current density and related microstructures of TFA-MOD YBCO coated conductors

Cited by 16 publications

References 9 publications

Liquid mediated growth and the bimodal microstructure of YBa₂Cu₃O_7−δ films made by the ex situ conversion of physical vapor deposited BaF₂ precursors

Liquid mediated growth and the bimodal microstructure of YBa₂Cu₃O_7−δ films made by the ex situ conversion of physical vapor deposited BaF₂ precursors

INFLUENCE OF COATING SOLUTION COMPOSITION ON REBa₂Cu₃O_y (RE=Gd AND Sm, Eu, Gd) FILMS FABRICATED BY FLUORINE-FREE METAL–ORGANIC DEPOSITION

9 Developments in high temperature superconductivity

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Critical current density and related microstructures of TFA-MOD YBCO coated conductors

Cited by 16 publications

References 9 publications

Liquid mediated growth and the bimodal microstructure of YBa2Cu3O7−δ films made by the ex situ conversion of physical vapor deposited BaF2 precursors

Liquid mediated growth and the bimodal microstructure of YBa2Cu3O7−δ films made by the ex situ conversion of physical vapor deposited BaF2 precursors

INFLUENCE OF COATING SOLUTION COMPOSITION ON REBa2Cu3Oy (RE=Gd AND Sm, Eu, Gd) FILMS FABRICATED BY FLUORINE-FREE METAL–ORGANIC DEPOSITION

9 Developments in high temperature superconductivity

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Liquid mediated growth and the bimodal microstructure of YBa₂Cu₃O_7−δ films made by the ex situ conversion of physical vapor deposited BaF₂ precursors

Liquid mediated growth and the bimodal microstructure of YBa₂Cu₃O_7−δ films made by the ex situ conversion of physical vapor deposited BaF₂ precursors

INFLUENCE OF COATING SOLUTION COMPOSITION ON REBa₂Cu₃O_y (RE=Gd AND Sm, Eu, Gd) FILMS FABRICATED BY FLUORINE-FREE METAL–ORGANIC DEPOSITION