Determination of oxygen content and cation valences in superconducting Tl-based cuprates by a wet chemical method

A. Fukuoka; M. Karppinen; M. Itoh; K. Hamada; H. Yamauchi

doi:10.1103/PhysRevB.51.12759

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Determination of oxygen content and cation valences in superconducting Tl-based cuprates by a wet chemical method

A. Fukuoka, M. Karppinen, M. Itoh, K. Hamada, H. Yamauchi

DOI 10.1103/PhysRevB.51.12759 · Physical Review B

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Abstract

A wet chemical route based on constant-potential electrolysis and different reactivities of Cu3+ and Tl3+ with water is proposed to distinguish the average valences of Cu and Tl in superconducting thallium cuprates. The validity of the method is demonstrated using YBa2Cu3Oy, Tl2O3, and Tl2O as reference materials for Cu3+, Tl3+, and Tl+, respectively. Furthermore, the oxygen contents and the cation valences have been determined for various Tl-22(n-1)n phases (where n=1–4). With increasing n value the Cu valence is found to decrease, while the valence of thallium remains rather constant at ca. +3, regardless of the value of n. Based on these results, the possible carrier doping mechanisms in the Tl-22(n-1)n phases are discussed.

Source-reported materials — not catalogue approval

Formula	Reported Tc (K)	Pressure (GPa)	Type
YBa2Cu3Oy Archive — visibility unverified Source-occurrence policy only; no material identity or catalogue acceptance is inferred from the formula.	—	Pressure not reported	unknown