TY - JOUR

T1 - Effect of isosymmetric phase transition in MIEC perovskite on the kinetic parameters of its interaction with oxygen

AU - Popov, Mikhail P.

AU - Gongola, Marko I.

AU - Kovalev, Ivan V.

AU - Guskov, Rostislav D.

AU - Chizhik, Stanislav A.

AU - Nemudry, Alexander P.

N1 - The research was supported by RSF № 22-73-10200, https://rscf.ru/project/22-73-10200/.

PY - 2023/11/1

Y1 - 2023/11/1

N2 - Oxygen partial pressure relaxation technique was used to study transient kinetics of re-equilibration in the reaction of nonstoichiometric oxide Ba0.5Sr0.5Co0.75Fe0.2Mo0.05O3-δ with oxygen within a region of 3-δ stoichiometry close to the nominal oxidation state 3+ for cobalt where an isosymmetric phase transition cubic perovskite P1 – cubic perovskite P2 is observed. The relaxation data were analyzed using a macrokinetic model that explicitly takes into account the power-law dependence of the surface reaction rate on the oxygen partial pressure. A twofold decrease in the power-law exponent (n = 0.7 to n = 0.3) was found at the point of the P1-P2 phase transition, which indicates a change in the mechanism of the rate-determining step of the reaction caused by the transition. At the same time, the functional dependence of the diffusion mobility of oxygen vacancies on the equilibrium oxygen pressure does not change at the transition point, which means that the transition does not affect the mechanism of bulk vacancy mobility.

AB - Oxygen partial pressure relaxation technique was used to study transient kinetics of re-equilibration in the reaction of nonstoichiometric oxide Ba0.5Sr0.5Co0.75Fe0.2Mo0.05O3-δ with oxygen within a region of 3-δ stoichiometry close to the nominal oxidation state 3+ for cobalt where an isosymmetric phase transition cubic perovskite P1 – cubic perovskite P2 is observed. The relaxation data were analyzed using a macrokinetic model that explicitly takes into account the power-law dependence of the surface reaction rate on the oxygen partial pressure. A twofold decrease in the power-law exponent (n = 0.7 to n = 0.3) was found at the point of the P1-P2 phase transition, which indicates a change in the mechanism of the rate-determining step of the reaction caused by the transition. At the same time, the functional dependence of the diffusion mobility of oxygen vacancies on the equilibrium oxygen pressure does not change at the transition point, which means that the transition does not affect the mechanism of bulk vacancy mobility.

KW - MIEC oxides

KW - OPPR

KW - Oxygen exchange

KW - Phase Transition

KW - Relaxation kinetics

UR - https://www.scopus.com/record/display.uri?eid=2-s2.0-85171652447&origin=inward&txGid=35329c53cb8fc27b0b59086d2f072c24

UR - https://www.mendeley.com/catalogue/3bbbde5d-4f03-3ab2-95fd-14f3a611d580/

U2 - 10.1016/j.cej.2023.146082

DO - 10.1016/j.cej.2023.146082

M3 - Article

VL - 475

JO - Chemical Engineering Journal

JF - Chemical Engineering Journal

SN - 1385-8947

M1 - 146082

ER -