Determination of non-stoichiometric oxygen in YBCO superconductors by coulometric titration

A coulometric titration method has been developed for the determination of non-stoichiometric oxygen in YBCO superconductors, The composition of the supporting electrolyte is 1 mol 1−1 HCl, 0.02 mol 1−1 CuSO4 and 0.17 mol 1−1 KBr. The powdered sample is introduced in the electrolytic cell containing a known excess of Cu(I), previously electrogenerated by galvanostatic reduction of Cu(II) ions, the sample is dissolved, and the non-reacted Cu(I) is back titrated with electrogenerated Br2. The method was applied to an analysis of monophase YBa2Cu3O6.5 + δ superconductor. Spectrophotometry without calibration is used as a comparative method. The reproducibility of the results for the non-stoichiometric oxygen content obtained by the suggested method is much better than that of the comparative method. The new method is very suitable for series of analysis.