Precision determination of copper in samples of high-Tc superconductors by potentiostatic coulometry
- V.I. Vernadskii Institute of Geochemistry and Analytical Chemistry, Moscow (Russian Federation)
An important task in the creation of high-Tc superconductors of required composition is the sufficiently accurate determination of the main components of high-Tc superconductors. One of the most widely encountered elements appearing in high-Tc superconductors is copper, whose precision determination is possible by coulometry. The coulometric determination of copper is generally accomplished by reducing Cu(II) or Cu(I) to the metal on electrodes prepared from various materials (Pt, C). There have been reports to the determination of macroscopic quantities of copper with the aid of coulometric titrations. The relative standard deviation (s{sub r}) in these procedures for determining copper exceeds 0.01. A procedure for the simultaneous determination of copper and indium in CuInS{sub 2} by controlled-potential coulometry on a large mercury electrode in NaCl solutions was proposed (s{sub r} did not exceed 0.05, and the range of determinable amounts of copper extended from 0.3 to 3 mg). The determination of copper by potentiostatic coulometry on an automated computer-controlled system using a gold indicator electrode was described by Subochev et al.. They proposed the use of 1 M HCl and the reversible reaction (1) CuCl {r_equilibrium} Cu{sup 2+} + Cl{sup {minus}} + e. for the coulometric determination of macroscopic and microgram quantities of copper. This case offers an optimal situation for coulometry, under which both forms of the redox system [the reactant and product forms, which are Cu(I) and Cu(II) in the present case], remain in the solution. This makes it possible to repeat determinations many times in single aliquot portion of the solution and thus to improve the metrological characteristics of the determinations. Here, the authors investigated the possibility of using reaction (1) and a Pt screen with a large surface as the working electrode to determine copper in high-Tc superconducting materials which also contain barium, yttrium, and thallium.
- OSTI ID:
- 39255
- Journal Information:
- Journal of Analytical Chemistry, Journal Name: Journal of Analytical Chemistry Journal Issue: 10 Vol. 48; ISSN 1061-9348; ISSN JACTE2
- Country of Publication:
- United States
- Language:
- English
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