Spectrophotometric determination of oxygen stoichiometry in YBCO superconducting bulk samples Original Research Article

The spectrophotometric method [Anal. Chim. Acta 336 (1996) 223] for the determination of the non-stoichiometric oxygen in YBa2Cu3O6.5+δ superconductors is discussed. Considerable improvements in the experimental conditions of the procedure for the bulk sample analyses are made. The potassium iodide is placed in the dry beaker instead of in the funnel, and its quantity is increased to 7.5 g. Nitrilothrieacetic acid or glycine is used as a ligand for the copper(II) ions instead of ethylendiaminetetraacetic acid. A differential mode only of the absorbance measurement is used. The blank sample solution is prepared simultaneously with the sample solution, passing through all the stages of the procedure. The δ-results for the oxygen coefficient of a monophase superconducting bulk sample obtained by the improved method are accurate and more precise than these of the previous method. Their accuracy is confirmed by coulometry.