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In the Laboratory
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Spectrophotometric Determination of the Hole Concentration in the Superconductor YBa2Cu3O7-x. An Undergraduate Experiment
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Jack I. Hoppé and Mounir A. Malati
Mid Kent College of Higher and Further Education, Horstead, Chatham, Kent ME5 9UQ, United Kingdom
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February 2005
Vol. 82 No. 2
p. 299
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| Abstract |
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The preparation and characterization of the superconductor YBa2Cu3O7-x, or YBCO, are described. The experiment is based on the reduction of the holes by FeCl2 in 1 M HCl solution under laboratory vacuum. This reaction leads to the formation of Fe(III) chloride, mainly in the form of tetrahedral [FeCl4]–, together with Cu(II) chloride, mainly in the form [CuCl4]2–. The electronic spectra of the two species, as well as Fe(II) chloride, are described. An intense absorption band for Fe(III) at 335 nm is well separated from a weaker band for Cu(II), and from an even weaker band for Fe(II). The absorbance at 335 nm of the solution resulting from the addition of HCl to solid YBCO subsequent to the above reaction, together with absorbances of standard FeCl3 in 1 M HCl, were used to calculate the concentration of Fe(III). This is equivalent to the hole concentration in the superconductor. The results are compared with those obtained by the well known iodometric method.
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| Supplement |
Instructions for the students and notes for the instructor are available.
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 Contents |
Folder JCE2005p0299W, containing JCE2005p0299W.doc (Microsoft Word) and JCE2005p0299W.cdr (Corel Draw)
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| More Information |
Citation |
Hoppé, Jack I.; Malati, Mounir A. J. Chem. Educ. 2005 82 299.
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Keywords |
Analytical Chemistry; Redox Reactions; Solid-State Chemistry
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History |
Created:
Last Updated: |
January 4, 2005
January 14, 2005
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| Home > JCE Print > Journal of Chemical Education > Issues >
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February
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299
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