Determination of the oxidizing ability of HTSC materials containing two elements with a variable degree of oxidation |
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Authors: | R P Pantaler N B Lebed A B Blank |
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Affiliation: | (1) Institute for Single Crystals, Lenin av. 60, 310 141 Kharkov, USSR |
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Abstract: | The presence of mixed valence states of elements is supposed to be a common characteristic feature of the high-T
c
superconductors, based on copper oxides. Methods have been suggested for the determination of Cu(III) in the Y-Ba-Cu-O ceramics
and separate determination of two oxidants: Bi(V) and Cu(III), Tl(III) and Cu(III) in the corresponding materials. Compounds
of Bi(V) oxidize in the ions of Mn(II) to MnO
4
−
in the acidic medium. Active oxygen, bound to Cu(III) is isolated, not oxidizing Mn(II). MnO
4
−
is titrated then with a solution of Fe(II) sulphate. For the determination of Tl(III) the sample is dissolved in the acid,
Cu(III) is reduced to Cu(II) and Tl(III) is titrated with the hydroquinone solution. The compounds of Bi(V), Tl(III) and Cu(III),
having high oxidation-reduction potentials can oxidize the complex Co(II)-EDTA to Co(III)-EDTA. The colour intensity of the
latter is proportional to the content of Cu(III) or to the sum of Bi(V) and Cu(III) or Tl(III) and Cu(III). The content of
Cu(III) in Bi- and Tl-containing materials is determined by the difference. |
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Keywords: | Oxidizing ability valence states of elements titrimetry spectrophotometry |
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