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Huijbregtse, J.M.; Klaassen, F.M.; Geest, R.C.F. van der; Dam, B.; Griessen, R.

doi:10.1023/a:1022572606787

Cited by 6 publications

(3 citation statements)

References 6 publications

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“…The defects responsible for the individual pinning in YBCO vary in nature. A linear correlation between B 0 and the density of threading dislocations in epitaxially grown YBCO films has been reported by Dam et al [81,131,132]. Krusin-Elbaum et al [133] reported a linear dependence of the B 0 of irradiated single crystals with the density of irradiation tracks.…”

Section: Critical Currents Of Ex Situ Processed Filmsmentioning

confidence: 74%

Growth of thick YBa₂Cu₃O₇layers via a barium fluoride process

Solovyov¹,

Dimitrov²,

Li³

2012

Supercond. Sci. Technol.

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The ex situ process has emerged as a popular technology for growing epitaxial YBa 2 Cu 3 O 7 (YBCO) for the second generation of coated conductors. The process combines low cost, ease of scale-up, the possibility of achieving high critical currents in relatively thick YBCO layers, as well as high tolerances to substrate misalignment. All of these factors explain why the process is increasingly becoming adapted by manufacturing companies for the production of YBCO wires. Studies of the barium fluoride variant of the ex situ process have offered rare insights into the structure, chemistry and pinning in ultra-thick, 5 µm, ex situ YBCO layers. The transition to thick YBCO layers is viewed as one of the key ingredients of the commercial success of the YBCO wire technology, which makes these studies especially relevant. This review is intended to be a comprehensive introduction into the history, physics and chemistry of barium fluoride processing, discussed concomitantly with recent results and trends in this field. Furthermore, comparisons are made between YBCO films made by ex situ and in situ deposition processes.

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Section: Critical Currents Of Ex Situ Processed Filmsmentioning

confidence: 74%

Growth of thick YBa₂Cu₃O₇layers via a barium fluoride process

Solovyov¹,

Dimitrov²,

Li³

2012

Supercond. Sci. Technol.

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“…Since the microscopic nature of the additional pinning centers related to the BZO incorporation is gener-ally attributed both to edge dislocations nucleated at the YBCO/BZO interface and to the c-axis elongated character or self-alignment of BZO crystallites, 2,3 we estimated the presence of linear defects in our YBCO/ BZO by repeated wet-chemical etching. 9 We found etch pits characteristic of linear defects parallel to the c-axis, with uniform distribution and areal density 30-40 times higher than in pristine YBCO. The film thickness was in the range were the growth technique yielded the most crystalline samples.…”

mentioning

confidence: 64%

Strong reduction of field-dependent microwave surface resistance in YBa2Cu3O7−δ with submicrometric BaZrO3 inclusions

et al. 2007

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We observe a strong reduction of the field induced thin film surface resistance measured at high microwave frequency (ν =47.7 GHz) in YBa2Cu3O 7−δ thin films grown on SrTiO3 substrates, as a consequence of the introduction of sub-micrometric BaZrO3 particles. The field increase of the surface resistance is smaller by a factor of ∼3 in the film with BaZrO3 inclusions, while the zerofield properties are not much affected. Combining surface resistance and surface reactance data we conclude (a) that BaZrO3 inclusions determine very deep and steep pinning wells and (b) that the pinning changes nature with respect to the pure film.Increasing pinning of vortex lines is an essential achievement for useful applications of superconductors in general, and of cuprate superconductors in particular due to the wide range of the H − T phase diagram where vortices are free or nearly free to move. Columnar defects are best suited to this aim, 1 but the introduction of such defects requires rather sophisticated techniques which are not suitable for mass production. Recently it was shown 2 that inclusions of BaZrO 3 (BZO) particles of dimensions in the 10-1000 nm range could determine a significant improvement of the dc properties of YBa 2 Cu 3 O 7−δ (YBCO) thin films. In particular, the critical current density 2,3 could be raised up to values useful for large scale dc applications, and the irreversibility line could be shifted above 10 T at 77 K. 4 A major interest comes from the easy incorporation of such sub-µm particles directly into the targets used for film deposition, thus making feasible the mass growth of very low losses superconductors. Pinning of vortices at high frequencies is desirable not only for devices operating in dc magnetic fields, but also because power handling is limited by depinning of selfnucleated vortices. In fact, tailored profiles of columnar defects have been shown to largely extend the linear regime at low microwave frequencies. 5 However, when the operating frequency increases, the dissipation due to oscillating vortices becomes increasingly difficult to reduce: with increasing frequency the amplitude of the vortex oscillation decreases, and becomes so small that only interactions between single vortices and pinning centers determine the response. In this regime the steepness of the pinning wells affects the balance between the reactive (elastic) and resistive (viscous) response, and the depth affects the creep of vortices. Even columnar defects, when the driving current oscillates in the high microwave range, determine at most a reduction of the dissipation of only ∼15%, as seen from measurements at * corresponding author. e-mail: silva@fis.uniroma3.it ∼50 GHz, 6 while in some cases the microwave dissipation raised after heavy-ion irradiation. 7 It seems reasonable to state that, up to now, no known artificial pinning centers have shown a significant reduction of the dissipation at very high frequencies. Measuring the response at the high edge of the microwave spectrum is a very stringent test for ...

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“…Instead the distribution is random only at long distances. 25 The sizes of these dislocations is 0.3-0.5 nm. 20 On the other hand, doping YBCO films with BZO leads to 5-10 nm wide BZO rods to be similarly positioned in the film.…”

Section: Pinning By Columnar Defectsmentioning

confidence: 98%

Modeling flux pinning in thin undoped and BaZrO3-doped YBCO films

Paturi

Irjala

Huhtinen

et al. 2009

Journal of Applied Physics

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A simple model based on distributions of twin boundaries, dislocations, and BaZrO 3 nanorods is presented to describe the J c properties of undoped and BaZrO 3 ͑BZO͒-doped YBa 2 Cu 3 O x thin films. The model accurately describes the shape of J c ͑B , T͒ curves of the films, when the pinning site distributions are taken from distributions of twin spacings and BZO nanorods from transmission electron microscope images. Thus, assuming that the model can be used for prediction of the J c properties, we conclude that for enhancement of undoped films more crystalline defects are needed and for doped films a dopant that would create slightly larger rods would be optimal.

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Untitled

Cited by 6 publications

References 6 publications

Growth of thick YBa₂Cu₃O₇layers via a barium fluoride process

Growth of thick YBa₂Cu₃O₇layers via a barium fluoride process

Strong reduction of field-dependent microwave surface resistance in YBa2Cu3O7−δ with submicrometric BaZrO3 inclusions

Modeling flux pinning in thin undoped and BaZrO3-doped YBCO films

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Untitled

Cited by 6 publications

References 6 publications

Growth of thick YBa2Cu3O7layers via a barium fluoride process

Growth of thick YBa2Cu3O7layers via a barium fluoride process

Strong reduction of field-dependent microwave surface resistance in YBa2Cu3O7−δ with submicrometric BaZrO3 inclusions

Modeling flux pinning in thin undoped and BaZrO3-doped YBCO films

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Growth of thick YBa₂Cu₃O₇layers via a barium fluoride process

Growth of thick YBa₂Cu₃O₇layers via a barium fluoride process