Determination of oxygen stoichiometry in YBCO superconductors by spectrophotometry

Nedeltcheva, T.

doi:10.1016/0003-2670(95)00237-t

Cited by 10 publications

(4 citation statements)

References 2 publications

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“…It is noticeable a preferential growth of the sample along the c -axis, corresponding to the (001) planes [43,44]. The Oxygen contents in both samples were obtained from the lattice parameters [45][46][47]. The obtained values are δ > 0.15 and δ ≤ 0.10 for the sintered and texturized samples, respectively, which agrees with the superconducting behaviour observed in these samples.…”

Section: Resultssupporting

confidence: 73%

Attraction and repulsion forces in melt-textured and sintered YBCO-superconductors: a comparative study

Arias-Arana

Rojas-Zambrano

Mariño-Camargo

2020

redin

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In this paper, we measure the attraction (suspension) and repulsion (levitation) forces produced by the interaction between a permanent magnet and different bulk superconductors. The measurements of the interaction force HTS-PM were carried out with a relatively simple technique developed by us, which is reproducible, reliable and low cost. The obtained results were analyzed with the Bean’s critical-state model assuming a uniform magnetic field applied to the superconductor. Two superconducting samples of YBa2Cu3O7-δ (YBCO) prepared by solid-state reaction method and by the melt-textured growth method (MTG) were used. Both samples presented a different hysteresis behaviour in the field cooling (FC) and zero field cooling (ZFC) regimes. Levitation and suspension phenomena were observed in the MTG sample; however, the sintered sample (S) with Oxygen deficiencies (δ > 0.15) displayed a slight levitation force but did not show a suspension force, the latter one attributed to a more efficient magnetic flux pinning. Additionally, the critical current density of both samples was determined from the maximum gap of the force (ΔF) in the FC regime. The obtained values were between 43.00 A/cm2 and 2,758 A/cm2 for the sintered and MTG samples, respectively. These values show a remarkable difference between sintered and MTG samples like that observed from magnetization measurements, which indicate that attraction and repulsion force measurements could provide a rapid and reliable characterization method of polycrystalline superconducting samples.

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Section: Resultssupporting

confidence: 73%

Attraction and repulsion forces in melt-textured and sintered YBCO-superconductors: a comparative study

Arias-Arana

Rojas-Zambrano

Mariño-Camargo

2020

redin

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“…Other superconducting and non-superconducting phases were not detected within the experimental sensitivity. The Oxygen contents in both samples were obtained from the lattice parameters [31][32][33]. The obtained values were δ > 0,15 and δ ≤ 0,10 for the S and MTG samples, respectively, which agrees with the superconducting behavior observed in these samples.…”

Section: Resultssupporting

confidence: 59%

Levitation and Suspension Forces Measurement System for High Tc Superconductors

Rojas

Arias

Mariño

2020

Momento

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The interaction forces, attraction (suspension) and repulsion (levitation) between a permanent magnet and different bulk Yttrium-based superconductors were carried out with an automatic system developed in our group, which is reproducible, reliable and low cost. Two superconducting samples of YBa 2 Cu 3 O 7−δ (YBCO) prepared by solid-state reaction method (S) and by the melt-textured growth method (MTG) were used. Both samples were characterized by XRD technique and presented the characteristic peaks and intensity relations of the YBCO-123 superconducting phase. Oxygen deficiencies δ > 0,15 and δ < 0,10 for the S and MTG samples respectively, were observed. Both samples displayed different hysteresis behavior in the Force (F ) vs. Distance (z) measurements when they were field cooled (FC) and zero field cooled (ZFC). This behavior agrees with hysteresis loops observed in magnetization measurements. Both levitation and suspension phenomena were observed in the MTG sample with large hysteresis loops of the force. On the contrary, the S sample with small hysteresis loops did not show a suspension force, only displayed a slight levitation force.

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“…Most such methods involve the extraction of oxygen from the sample using dissolution and a chemical method to calculate the oxygen content. Examples are the reduction of samples in a hydrogen flow (Graf, Triscone, & Muller, 1990), iodometric titration (Benzi et al, 2004) or spectrophotometrywhich involves dissolution of YBCO in acid solvents then wavelength absorbance measurements (Nedeltcheva, 1995;Nedeltcheva & Vladimirova, 2001). These methods provide an average value of oxygen content over large sample volumes, giving no indication of localised segregation effects nor the distribution of point defects, and are likely insufficient for property predictions unless the sample is microscopically and macroscopically uniform.…”

Section: Introductionmentioning

confidence: 99%

Nanoscale Stoichiometric Analysis of a High-Temperature Superconductor by Atom Probe Tomography

et al. 2017

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The functional properties of the high-temperature superconductor Y1Ba2Cu3O7-δ (Y-123) are closely correlated to the exact stoichiometry and oxygen content. Exceeding the critical value of 1 oxygen vacancy for every five unit cells (δ>0.2, which translates to a 1.5 at% deviation from the nominal oxygen stoichiometry of Y7.7Ba15.3Cu23O54-δ ) is sufficient to alter the superconducting properties. Stoichiometry at the nanometer scale, particularly of oxygen and other lighter elements, is extremely difficult to quantify in complex functional ceramics by most currently available analytical techniques. The present study is an analysis and optimization of the experimental conditions required to quantify the local nanoscale stoichiometry of single crystal yttrium barium copper oxide (YBCO) samples in three dimensions by atom probe tomography (APT). APT analysis required systematic exploration of a wide range of data acquisition and processing conditions to calibrate the measurements. Laser pulse energy, ion identification, and the choice of range widths were all found to influence composition measurements. The final composition obtained from melt-grown crystals with optimized superconducting properties was Y7.9Ba10.4Cu24.4O57.2.

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Determination of oxygen stoichiometry in YBCO superconductors by spectrophotometry

Cited by 10 publications

References 2 publications

Attraction and repulsion forces in melt-textured and sintered YBCO-superconductors: a comparative study

Attraction and repulsion forces in melt-textured and sintered YBCO-superconductors: a comparative study

Levitation and Suspension Forces Measurement System for High Tc Superconductors

Nanoscale Stoichiometric Analysis of a High-Temperature Superconductor by Atom Probe Tomography

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