Spectrophotometric determination of oxygen stoichiometry in YBCO superconducting bulk samples

Synthesis and superconducting properties of Nd0.33Eu0.08Gd0.58Ba2Cu3Oz materials

“…The chemical composition of the samples was determined by the X-ray microanalyses and using energy dispersive spectroscopy (EDS) on a LINK Analytical AN10000 system. The oxygen content was determined with spectrophotometric method [9,10]. Temperature dependence of critical current density at zero magnetic fields was measured in specially designed device from 77 K up to T using four-probe contact method.…”

Spectrophotometric determination of oxygen content in calcium substituted RBCO (R=Eu, Gd, Er) superconductors

“…The assembly for sample dissolution is illustrated in Fig.1 [8]. To prevent iodine elemination by the action of light, the beaker was covered with dark paper.…”

“…It has been determined [4] that there is an existing relationship between the T c -value and the oxygen content in YBCO superconducting bulk samples. To test the relationship between the T c -value and the oxygen content in Ca-substituted RBCO samples, the methods, already known in the determination of the oxygen content in YBCO bulk samples [5][6][7][8], were applied [1,2,3,9]. The y-values in R 1−x Ca x Ba 2 Cu 3 O y (R = Y, Eu, Er, Gd; x=0 or 0.2) bulk samples were determined by iodometric titrations [1,2].…”

“…The y-values in R 1−x Ca x Ba 2 Cu 3 O y (R = Y, Eu, Er, Gd; x=0 or 0.2) bulk samples were determined by iodometric titrations [1,2]. The oxygen content in Y 1−x Ca x Ba 2 Cu 3 O y (x=0-0.3) was determined [3,9] by the spectrophotometric method [8] that was based on the absorbance measurement of solutions containing the yellow coloured I − 3 complex. This method was preferred because it did not require any calibration and a precise measurement of the sample mass.…”

“…As the chemical properties of Ca 2+ and Ba 2+ , as well as those of Y 3+ and Gd 3+ , Er 3+ , Eu 3+ are very similar, it was expected that the spectrophotometric method to determine the oxygen content in YBCO [8] could be applied to calcium substituted RCaBCO (R = Eu, Er, Gd) samples. The purpose of this report is to determine the oxygen content in R 1−x Ca x Ba 2 Cu 3 O y (R = Eu; Er; Gd and x=0; 0.2; 0.25; 0.3) bulk samples by the spectrophotometric method and to study the dependence of T c from the oxygen content (y) and the content of the included calcium (x).…”