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On the Quasichemical Model of Oxygen Absorption and Ordering in a High Temperature Superconductor YBa 2 Cu 3 O 6+ x
Author(s) -
Andreev L. A.,
Nechaev Yu. S.,
Kalashnikova E. A.,
Konovalov N. T.,
Lykhin V. A.,
Mineav Yu. A.,
Olshevskii N. A.
Publication year - 1991
Publication title -
physica status solidi (b)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.51
H-Index - 109
eISSN - 1521-3951
pISSN - 0370-1972
DOI - 10.1002/pssb.2221630122
Subject(s) - tetragonal crystal system , oxygen , solid oxygen , absorption (acoustics) , orthorhombic crystal system , phase diagram , materials science , absorption spectroscopy , thermodynamics , analytical chemistry (journal) , chemistry , phase (matter) , crystallography , crystal structure , physics , optics , organic chemistry , chromatography , composite material
In the framework of the quasichemical Williams‐Bragg model an equation is obtained for the isotherm of gas absorption by the interstitials of the solvent lattice with the effect of ordering recognized; the equation is applied to analysis and interpretation of experimental data on oxygen absorption and ordering in superconducting YBa 2 Cu 3 O 6+ x ceramics. The oxygen absorption in both, tetragonal and orthorhombic structures is described by an absorption isotherm which fits the Langmuir equation. Extreme concentratios of the “absorption centers” are found as the oxygen absorption energy and entropy in the tetragonal (T) and orthorhomic (O) phases. The ordering of absorbed oxygen is shown to be unrelated with the “oxygenoxygen” pairwise interaction and is attributable to the “T → O” transition. The experimental isotherms of oxygen absorption by the ceramics lead to elements of the “temperature–concentration ( X )” phase diagram which characterize the boundary between the T‐ and O‐phase regions.