Study of Mobile Oxygen in Ordered/Disordered Nonstoichiometric Sr-Gd-Cobaltate by Simultaneous Thermal Analysis

Vereshchagin, Sergei N.; Dudnikov, Vyacheslav A.; Solovyov, Leonid A. JOURNAL OF SIBERIAN FEDERAL UNIVERSITY-CHEMISTRY 10 (3):346-357; 10.17516/1998-2836-0031 2017

Simultaneous thermal analysis (DSC/TG/mass-spectroscopy) under variable pressure was applied to study properties of mobile oxygen in cubic disordered and tetragonal A-site ordered Sr-Gd-cobaltate (Sr/Gd=4). It was shown that A-site cation ordering results in a decrease of an enthalpy of oxygen elimination, predominant localization of created anion vacancies only at one of four unequivalent crystallographic O-sites and depletion of amount of mobile oxygen, which can be removed at a reduced pressure. The observed properties of mobile oxygen and catalytic activity in reaction of methane deep oxidation for ordered/disordered perovskite phases are discussed in connection with a local environment of O2- crystallographic sites with a different number of Gd3+ cations nearby