Determination of Average Valences of Copper and Thallium Separately in the Superconducting Thallium Cuprates
A novel wet chemical route based on potentiostatic electrolysis and different reactivities with water is proposed to distinguish the average valences of copper and thallium in thallium cuprates. In the first experiment the sum of the extra oxidation states above +2 for copper and +I for thallium is obtained by reducing both Cu3+ and Tl3+ with CuCl. As a result, we can estimate the oxygen content of the sample, In the second experiment Cu3+ is allowed to react completely with water before CuCl is added to determine the remaining oxidation power of the solution and thereby the valence of thallium. In both experiments, the excess of Cu1+ is electrolyzed as a final analysis step. The validity of the method is demonstrated with experimental results on YBa2Cu3Oz, Tl2O and Tl2O3, which are the reference materials for Cu2+, Tl1+ and Tl3+, respectively. The average valence of Cu and T1 in the properties of superconducting thallium cuprates with double Tl-O layers, i.e. Tl2Ba2Can−1CunOz(n=1–4), are successfully determined using this new technique.
KeywordsInduction Couple Plasma Conventional Solid State Reaction Coulometric Titration Conventional Solid State Reaction Method Solid State Reaction Technique
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