Effect of oxygen pressure on the synthesis of YBa2Cu3O7−<i>x</i> thin films by post-deposition annealing

Feenstra, R.; Lindemer, T.B.; Budai, J. D.; Galloway, Michael

doi:10.1063/1.348868

Cited by 263 publications

(115 citation statements)

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“…[8][9][10][11] In this letter, we report ion-milling studies on YBCO grown by the BaF 2 ex situ process on IBAD-YSZ buffered metal substrates. The details of the BaF 2 ex situ growth process 7,12 and preparation of IBAD-YSZ buffered metal tapes 13 are given elsewhere. Briefly, precursor layers of the desired thickness were prepared by vacuum deposition using three electronbeam sources onto a ''cold'' substrate; the layers were subsequently converted into epitaxial YBCO by annealing in a furnace under flowing gas conditions at atmospheric pressure.…”

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confidence: 99%

Through-thickness superconducting and normal-state transport properties revealed by thinning of thick film ex situ YBa2Cu3O7−x coated conductors

Larbalestier

Feenstra

Gapud

et al. 2003

Applied Physics Letters

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A rapid decrease in the critical current density (J c ) of YBa 2 Cu 3 O 7Ϫx ͑YBCO͒ films with increasing film thickness has been observed for multiple YBCO growth processes. While such behavior is predicted from two-dimensional collective pinning models under certain assumptions, empirical observations of the thickness dependence of J c are believed to be largely processing dependent at present. To investigate this behavior in ex situ YBCO films, 2.0-and 2.9-m-thick YBCO films on ion beam assisted deposition-yttria stabilized zirconia substrates were thinned and repeatedly measured for (T) and J c (H). The 2.9 m film exhibited a constant J c ͓77 K, self-field (SF)͔ through thickness of ϳ1 MA/cm 2 while the 2.0 m film exhibited an increase in J c (77 K, SF) as it was thinned. Neither film offered evidence of significant dead layers, suggesting that further increases in critical current can be obtained by growing thicker YBCO layers. © 2003 American Institute of Physics. ͓DOI: 10.1063/1.1625103͔ Coated conductors ͑CCs͒, or second generation high temperature superconducting wires, hold great promise for commercial applications and electric power applications, such as transmission lines, transformers and motors. To meet the technical requirements of these applications, CCs need to deliver large critical current (I c ) values.1 An obvious approach to improving I c is to increase the thickness t of the superconductor layer, but for several YBa 2 Cu 3 O 7Ϫx ͑YBCO͒ growth processes, [2][3][4][5][6][7] there is a strong decrease in the critical current density J c with increasing film thickness t.Most knowledge of the thickness dependence of the critical current density of YBCO films comes from studies of multiple films produced with different YBCO layer thickness.2,3,6,7 A complementary approach to investigate J c (t) was employed by Foltyn et al. 4 Using ion milling, thick YBCO films were successively thinned and J c measured at multiple thickness on a single sample. This second approach also produces a variable thickness dataset, however, with reduced emphasis on thickness dependent trends in the growth, but enhanced emphasis on through-thickness homogeneity. The YBCO in Ref. 4 was grown by pulsed laser deposition ͑PLD͒ on metal tapes buffered with yttriastabilized zirconia ͑YSZ͒ textured by ion-beam-assisted deposition ͑IBAD͒. Strong structural degradation was observed in the films, most significantly in the form of ''deadlayers'' (I c ϭJ c ϭ0) at both the film surface and the buffer layer interface. Subsequent work by Foltyn and others has shown that these ''dead'' layers are not endemic of thick YBCO coated conductors, but instead dependent on the growth conditions. [8][9][10][11] In this letter, we report ion-milling studies on YBCO grown by the BaF 2 ex situ process on IBAD-YSZ buffered metal substrates. The details of the BaF 2 ex situ growth process 7,12 and preparation of IBAD-YSZ buffered metal tapes 13 are given elsewhere. Briefly, precursor layers of the desired thickness were prepared by vacuum deposition ...

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Through-thickness superconducting and normal-state transport properties revealed by thinning of thick film ex situ YBa2Cu3O7−x coated conductors

Larbalestier

Feenstra

Gapud

et al. 2003

Applied Physics Letters

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“…All samples consisted of a deformation textured Ni substrate with a Ni/CeO 2 or Y 2 O 3 /yttria-stabilized zirconia (YSZ)/CeO 2 buffer layer structure. The YBCO layers were grown by the barium fluoride 6 or trifluoroacetate 7 methods. All patterned links ͑inter-and intragrain͒ were 10 m wide and 30 m long.…”

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Inter- and intragrain transport measurements in YBa2Cu3O7−x deformation textured coated conductors

Feldmann

Larbalestier

Verebelyi

et al. 2001

Applied Physics Letters

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Coated conductors ͑CCs͒ using deformation textured substrates such as rolling assisted biaxially textured substrates ͑RABiTS™͒ are one of the most suitable conductor forms for applications at 77 K. These substrates are inherently polycrystalline and produce a network of grain boundaries ͑GBs͒ in the YBa 2 Cu 3 O 7Ϫx ͑YBCO͒ layer. 1,2 Magnetooptical ͑MO͒ studies demonstrate that the vast majority of these GBs have a J c value less than that of the intragrain 1,2 regions. Under applied transport currents, MO imaging of the self-field shows a strong GB influence and a clear illustration of percolative current flow. 2,3 The self-field studies have shown that J c is usually limited in a local region by a small fraction of GBs, and that the majority of the sample is carrying a current much less than its local J c . Here we expand upon that earlier work by quantifying the inter-and intragrain J c values of several CC samples. This study shows that the intragrain J c is not the limiting factor in present CC technology, and the J c ( ) dependence of GBs in YBCO CCs fits well with previous studies of YBCO grown on ͓001͔ tilt SrTiO 3 ͑STO͒ bicrystals. 4,5 Standard optical photolithography and dry etching was used to pattern inter-and intragrain links in several CC samples. All samples consisted of a deformation textured Ni substrate with a Ni/CeO 2 or Y 2 O 3 /yttria-stabilized zirconia (YSZ)/CeO 2 buffer layer structure. The YBCO layers were grown by the barium fluoride 6 or trifluoroacetate 7 methods. All patterned links ͑inter-and intragrain͒ were 10 m wide and 30 m long. Extended voltage-current characteristics and J c (H) dependencies were measured. For intragrain links, J c values were determined using an electric field criterion of 1 V/cm. For a 30 m long link, this yields a voltage criterion of 3 nV, well above our typical measurement noise of 0.3-0.5 nV. For the intergrain links, a voltage criterion ͑3 nV͒ was used due to the uncertainty in the width of the GBs. Universal use of the 1 V/cm criterion is crucial to legitimate, quantitative comparisons of J c values. Also, it is well known that J c increases with decreasing film thickness, 8 and Zhao et al. have observed significant overestimates of J c for links less than 10 m wide due errors introduced in patterning. 9 All these factors need to be considered when comparing J c values. For intergrain links, electron backscatter Kikuchi pattern ͑EBKP͒ analysis was used to determine the GB misorientation angle . Where possible this was done in the YBCO layer; however, due to poor EBKP quality most angles were measured in the YSZ. We admit this may not be a true representation of the GB angle in the YBCO. X-ray diffraction and recent EBKP studies 10 have shown that in general, there is an improvement in the c-axis alignment of the YBCO relative to the YSZ layer, and this results in a reduction of . Table I lists several properties of the samples and patterned links investigated. At least two links were patterned per sample, but not all links were suitable for study due...

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“…These results can be interpreted in terms of the phase diagram of YBCO, O 2 partial pressure vs. the reciprocal temperature, reported by Hammond and Bormann [5], Matijasevic et al [6], and Feenstra et al [7].…”

Section: Resultsmentioning

confidence: 99%

“…Kuhle et al reported the effect of Ar dilution in PLA deposition using O 2 gas on the surface morphology and the superconducting properties [4]. The effect of oxidation gas pressure for in situ preparation [5,6] and post-deposition annealing [7] of the YBa 2 Cu 3 O x (YBCO) films in various oxidation environments were also investigated. In most of these experiments, the excitation effect and the thermodynamical effect of ambient oxidation gas on the structure and properties of YBCO films are not necessarily discriminated.…”

Section: Introductionmentioning

confidence: 99%

Low-temperature growth of YBCO thin films by pulsed laser ablation in reducing environment

Morimoto¹,

Takezawa²,

Minamikawa³

et al. 1998

Applied Surface Science

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The effect of ambient gas on the preparation of YBa 2 Cu 3 O x (YBCO) high-T c superconducting thin films by pulsed laser ablation was explored in gas mixtures of argon + oxygen, argon + nitrous oxide, and nitrous oxide + oxygen. These experiments revealed that a reducing environment for the preparation of YBCO films enhances the film growth with the high temperature phase (trilayered perovskite YBCO) rather than the low temperature phase (cubic YBCO). This phenomenon is explained in terms of thermodynamic phase diagram. The effect of nitrous oxide on the thermodynamic phase diagram is far smaller than that of oxygen by a factor of two to three orders of magnitude.

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Effect of oxygen pressure on the synthesis of YBa2Cu3O7−x thin films by post-deposition annealing

Cited by 263 publications

References 65 publications

Through-thickness superconducting and normal-state transport properties revealed by thinning of thick film ex situ YBa2Cu3O7−x coated conductors

Through-thickness superconducting and normal-state transport properties revealed by thinning of thick film ex situ YBa2Cu3O7−x coated conductors

Inter- and intragrain transport measurements in YBa2Cu3O7−x deformation textured coated conductors

Low-temperature growth of YBCO thin films by pulsed laser ablation in reducing environment

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