Oxygen diffusion in c-axis-oriented YBa2Cu3Oxfilms

Chen, Yexin; Zhang, Jihua; Wu, Ziliang

doi:10.1088/0953-2048/5/8/001

Cited by 12 publications

(12 citation statements)

References 7 publications

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“…This idea has been realized in many groups by substituting fluorine-free salt(s) for one or two specific TFA salt(s) in the precursor solution. To the best of our knowledge, there were mainly three routes of metal salt substitution(s): (1) Cu salt [7]; (2) Cu and Y salts [8,9]; (3) Cu and Ba salts [10]. Relative to the conventional TFA-MOD solution (100% fluorine content), the fluorine contents in these precursor solutions could be estimated to be about 53.8%, 30.8% (or 23.1% if the poor-Ba stoichiometry is used [11]) and 23.1%, respectively.…”

Section: Introductionmentioning

confidence: 99%

A low-fluorine solution with a 2:1 F/Ba mole ratio for the fabrication of YBCO films

Feng

Zhao

et al. 2014

Supercond. Sci. Technol.

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In the reported low-fluorine MOD-YBCO studies, the lowest F/Ba mole ratio of the precursor solution was 4.5. However, further lowering the F/Ba ratio is important according to the researches of YBCO thick film. On the other hand, the F/Ba ratio is necessary to be at least 2 for the full conversion of the Ba precursor to BaF2 to avoid the formation of BaCO3, which is detrimental to the superconducting performance. In this study, a novel solution with the F/Ba mole ratio of 2 was developed, in which the fluorine content was only about 10.3% of that used in the conventional TFA-MOD method. Attenuated total reflectance-Fourier transformed-infrared spectra(ATR-FT-IR) revealed that BaCO3 was remarkably suppressed in the as-pyrolyzed film and eliminated at 700 • C. Thus YBCO films with a critical current density (Jc) over 5 MA cm −2 (77 K, 0 T, 200 nm thickness) could be obtained on LAO single crystal substrates. In-situ FT-IR spectra showed that no obvious fluorinated gaseous by-products were detected in the pyrolysis step, which indicated that all of the F atoms might remain in the film as fluorides. X-ray diffraction (XRD) θ/2θ scan showed that BaF2, but neither YF3 nor CuF2, was detected in the films quenched at 400 -800 • C. The formation priority of BaF2 over YF3 and CuF2 was interpreted by the chemical equilibrium of the potential reactions. Our study could enlarge the synthesis window of the precursor solution for MOD-YBCO fabrication and open a gate to study the fluorine content in the precursor solution continuously and systematically.

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Section: Introductionmentioning

confidence: 99%

A low-fluorine solution with a 2:1 F/Ba mole ratio for the fabrication of YBCO films

Feng

Zhao

et al. 2014

Supercond. Sci. Technol.

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“…We can classify these data according to the following four groups: powders [5,8,11], polycrystalline ceramics [7-9, 14, 16, 23], thin films [4,6,13,15,17,21,35,36] and single crystals [2,3,22].…”

Section: Resultsmentioning

confidence: 99%

“…However, because of an imperfect crystal structure (due to microcracks, twin and low-angle grain boundaries, acting as 'chimneys' in the c-direction) L can be much smaller than the lateral sample size [34][35][36]. Since L depends sensitively on the microstructure of the sample, it may vary considerably between different samples and may be the main source for the large variations of the oxygen diffusion coefficient reported in the literature.…”

Section: Theoretical Aspectsmentioning

confidence: 99%

Fe Deposition or Implantation into Vacuum Arc Deposited Cr Films

Heck¹,

Chayahara²,

Horino³

et al. 2003

Jpn. J. Appl. Phys.

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From isothermal four-point electric resistivity measurements we have determined the chemical diffusion coefficients for the in-and out-diffusion of oxygen in epitaxial c-axis oriented films of YBa 2 Cu 3 O 7−δ in the temperature range 500-650 K. At constant oxygen pressure we have observed the temporal changes in resistivity, following small steps upwards or downwards in temperature. At 600 K for the in-and out-diffusion of oxygen we found about the same diffusion coefficient D ab = 2 × 10 −14 cm 2 s −1 . The temperature dependence of D ab could be well fitted by an Arrhenius law, yielding the same activation energy E A = 1.1 eV for the inand out-diffusion.

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“…The bulk diffusion of oxygen in YBCO 6ϩx is highly anisotropic and takes place predominately in the ab plane, especially at temperatures below 670 K. 30 However, c-axis-oriented YBCO 6ϩx films consist of various grains whose mosaic boundaries act as short circuits for oxygen diffusion. 31,32 Typical activation energies for bulk and interface diffusion of oxygen in YBCO 6ϩx are about 1 eV. [33][34][35] It was observed that activation energies for oxygen out-diffusion are higher than those for oxygen in-diffusion.…”

Section: ͑6͒mentioning

confidence: 99%

Desorption of oxygen fromYBa2Cu3
Böck
¹
,
Kürsten
²
,
Brühl
³

et al. 1996
Phys. Rev. B

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Phonons of laser-deposited YBa 2 Cu 3 O 6ϩx films on MgO͑100͒ substrates are investigated in a Raman setup as a function of laser power density. Investigations of YBa 2 Cu 3 O 7 films allow us to study oxygen out-diffusion, where the onset of out-diffusion is indicated by the appearance of disorder-induced modes in the Raman spectra. At a pressure of 5ϫ10 Ϫ6 mbar the temperature threshold of the out-diffusion is (490Ϯ15) K. With increasing oxygen pressure the observed temperature thresholds rise only moderately in contrast to the behavior expected from the p ox -T phase diagram of YBa 2 Cu 3 O 6ϩx . Even at 1 bar oxygen partial pressure outdiffusion is observed and tetragonal sites with xϭ0 develop. These observations can be explained by photonstimulated desorption of oxygen. Investigations of YBa 2 Cu 3 O 6 films allow us to study oxygen in-diffusion. In 1 bar oxygen we observe competing oxygen fluxes due to thermally activated diffusion and photon-stimulated desorption. From these measurements we determine an upper bound of the thermal activation energy of the oxygen in-diffusion into YBa 2

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Oxygen diffusion in c-axis-oriented YBa₂Cu₃O_xfilms

Cited by 12 publications

References 7 publications

A low-fluorine solution with a 2:1 F/Ba mole ratio for the fabrication of YBCO films

A low-fluorine solution with a 2:1 F/Ba mole ratio for the fabrication of YBCO films

Fe Deposition or Implantation into Vacuum Arc Deposited Cr Films

Desorption of oxygen fromYBa2Cu3
Böck
¹
,
Kürsten
²
,
Brühl
³

et al. 1996
Phys. Rev. B

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Oxygen diffusion in c-axis-oriented YBa2Cu3Oxfilms

Cited by 12 publications

References 7 publications

A low-fluorine solution with a 2:1 F/Ba mole ratio for the fabrication of YBCO films

A low-fluorine solution with a 2:1 F/Ba mole ratio for the fabrication of YBCO films

Fe Deposition or Implantation into Vacuum Arc Deposited Cr Films

Desorption of oxygen fromYBa2Cu3Böck1, Kürsten2, Brühl3 et al. 1996Phys. Rev. B

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Oxygen diffusion in c-axis-oriented YBa₂Cu₃O_xfilms

Desorption of oxygen fromYBa2Cu3
Böck
¹
,
Kürsten
²
,
Brühl
³

et al. 1996
Phys. Rev. B