Water determination of precursor solutions with oxidant cations by the Karl Fischer method: the YBCO-TFA case
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Uncontrolled water content in non-aqueous precursor solutions can be a source of irreproducibility in thin film performance through changes in the gel network. Towards gaining control on the solution properties, water determination in metalorganic solutions of YBCO-TFA has been studied by the Karl Fischer titration in a volumetric-type unit. However, oxidizing cations usually present when preparing functional oxides by chemical solution routes severely interfere in the Karl Fischer analysis. In the case of YBCO-TFA, cupric ions in the initial solution oxidize the iodide produced in the Karl Fischer reaction back to iodine, which in turn feeds the titration reaction and consumes more water, causing a negative error in the analysis, which can be as large as 70%. However, such chemical interference of cupric salts can be modelled and quantified. A corrected Karl Fischer methodology is proposed for accurately measuring water content in YBCO-TFA solutions, which could be potentially extended to other precursor solutions containing oxidant cations.
KeywordsWater determination Metalorganic decomposition Characterization Karl Fischer YBCO-TFA
The authors acknowledge financial support from Spanish Ministerio de Educación y Ciencia (MAT2008.01022/NAN, CSD2007-00041, MAT2005-02047, NAN2004-09133-C03-01 and I3P-JAE), Generalitat de Catalunya (2005SGR0029 and XaRMAE) and EU HIPERCHEM (NMP-CT2005-516858). A. C. wishes to thank Ministerio de Ciencia e Innovación for the Spanish Ramón y Cajal program, Dr. Mark Rikel from Nexans Superconductors GmbH for valuable discussions and Dr. Marta Figueredo from the Organic Chemistry Department of the Autonomous University of Barcelona for the use of the Karl Fischer titration unit.
- 2.Obradors O, Puig T, Pomar A, Sandiumenge F, Mestres N, Coll M, Cavallaro A, Romà N, Gázquez J, González JC, Castaño O, Gutiérrez J, Palau A, Zalamova K, Morlens S, Hassini A, Gibert M, Ricart S, Moretó JM, Piñol S, Isfort D, Bock J (2006) Supercond Sci Technol 19:S13–S26. doi: 10.1088/0953-2048/19/3/003 CrossRefADSGoogle Scholar
- 9.Karl Fischer reagents—technical manual, Mitsubishi Chemical Corporation, Tokyo. http://www.mcckf.com/english/scope.html. Accessed 15 Jan 2009