Please use this identifier to cite or link to this item: http://hdl.handle.net/10995/51039
Title: Oxygen nonstoichiometry, crystal and defect structure of the double perovskite GdBaCo 1.8Fe 0.2O 6 - δ
Authors: Tsvetkov, D. S.
Ivanov, I. L.
Zuev, A. Y.
Issue Date: 2012
Citation: Tsvetkov D. S. Oxygen nonstoichiometry, crystal and defect structure of the double perovskite GdBaCo 1.8Fe 0.2O 6 - δ / D. S. Tsvetkov, I. L. Ivanov, A. Y. Zuev // Solid State Ionics. — 2012. — Vol. 218. — P. 13-17.
Abstract: Crystal structure of the double perovskite GdBaCo 1.8Fe 0.2O 6 - δ was investigated by means of in situ X-ray diffraction at temperatures between 25 and 800°C in air. Pmmm-P4/mmm phase transition was found to occur in GdBaCo 1.8Fe 0.2O 6 - δ at 515°C. The results of oxygen nonstoichiometry, δ, measured as a function of oxygen partial pressure, p O2, in temperature range 700 ≤ T,°C ≤ 1025 by means of thermogravimetric technique are presented for this double perovskite. Partial molar enthalpy and entropy of oxygen in the GdBaCo 1.8Fe 0.2O 6 - δ structure were calculated. Both thermodynamic properties were shown to increase dramatically in the vicinity of the oxygen nonstoichiometry value equal to 1. The p O2 dependences of oxygen nonstoichiometry were found to have inflections when the oxygen content of GdBaCo 1.8Fe 0.2O 6 - δ is equal to 5.0 exactly. The analysis of the defect structure of the double perovskite GdBaCo 1.8Fe 0.2O 6 - δ was carried out using the model based on the simple cubic perovskite GdCoO 3 as a reference state. Equilibrium constants of the appropriate defects reactions were, therefore, determined. As a consequence, concentrations of all defect species defined within the framework of the model proposed were calculated as functions of temperature and oxygen nonstoichiometry. Oxygen vacancies were shown to be formed during p O2 diminution in gas environment in the layers of GdBaCo 1.8Fe 0.2O 6 - δ crystal lattice where they are ordered until oxygen nonstoichiometry of the oxide becomes equal to unity afterwards oxygen vacancies are formed randomly in oxygen polyhedrons. © 2012 Elsevier B.V. All rights reserved.
Keywords: COULOMETRIC TITRATION
DEFECT STRUCTURE
DOUBLE PEROVSKITE
OXYGEN NONSTOICHIOMETRY
PARTIAL MOLAR QUANTITIES
URI: http://hdl.handle.net/10995/51039
metadata.dc.rights: info:eu-repo/semantics/restrictedAccess
SCOPUS ID: 84861392542
WOS ID: WOS:000306824000003
PURE ID: 1081355
ISSN: 0167-2738
DOI: 10.1016/j.ssi.2012.04.024
Appears in Collections:Научные публикации, проиндексированные в SCOPUS и WoS CC

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