Local structure of YBa2Cu3Oy with varying oxygen content and substitutional dopants on the Cu sites

Boyce, J. B.; Bridges, F.; Claeson, T.; Howland, R.S.; Geballe, T. H.; Nygren, Mats

doi:10.1016/s0921-4534(88)80121-7

Cited by 10 publications

(1 citation statement)

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“…Some authors consider c, pper to be in a mixed valence state: + 2 and + 3. The data of X-ray electron spectroscopy (Boyce et al 1988;Jaeger 1989; Dobrotvorskaya et al 1988), X-ray absorption spectroscopy (Maeda et al 1987;Lengeler et al 1988) and other methods give evidence in favour of this assumption. According to the other model the electric neutrality of the compound Y Ba-Cu O is ensured by the presence of oxygen in an abnormal degree of oxidation -1, included in the complex Cu 2 + -O- (Bianconi et a11987).…”

Section: Introductionmentioning

confidence: 99%

Determination of the oxidizing ability of HTSC materials containing two elements with a variable degree of oxidation

Pantaler¹,

Lebed²,

Blank³

1991

Bull. Mater. Sci.

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The presence of mixed valence states of elements is supposed to be a common characteristic feature of the high-Tc superconductors, based on copper oxides. Methods have been suggested for the determination of Cu(llI) in the Y-Ba-Cu-O ceramics and separate determination of two oxidants: Bi(V) and Cu(llI), TI(IlI) and Cu(llI) in the corresponding materials. Compounds of Bi(V) oxidize in the ions of Mn(II) to MnO2 in the acidic medium. Active oxygen, bound to Cu(Ill) is isolated, not oxidizing Mn(ll). MnO,~ is titrated then with a solution of Felll) sulphate. For the determination of TI(III) the sample is dissolved in the acid, Cu(III) is reduced to Cu(ll) and TI(III) is titrated with the hydroquinone solution. The compounds of Bi(V), TI(IIIt and Cu(lll), 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(Ill) or to the sum of Bi(V) and Cu(llI) or TI(III) and Cu(llIt. The content of Cu(III) in Bi-and Tl-containing materials is determined by the difference.

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Section: Introductionmentioning

confidence: 99%