Surface recrystallization - an underestimated phenomenon affecting oxygen exchange activity

Research output: Contribution to journalJournal article – Annual report year: 2019Researchpeer-review

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Surface recrystallization - an underestimated phenomenon affecting oxygen exchange activity. / Tripkovic, Dordije; Kungas, Rainer; Mogensen, Mogens Bjerg; Hendriksen, Peter Vang.

In: Journal of Materials Chemistry A, Vol. 7, No. 19, 2019, p. 11782-11791.

Research output: Contribution to journalJournal article – Annual report year: 2019Researchpeer-review

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@article{c0c9db8edff346209a0deeaaa14e716a,
title = "Surface recrystallization - an underestimated phenomenon affecting oxygen exchange activity",
abstract = "The rate of oxygen surface exchange on (La0.6Sr0.4)(0.99)CoO3- (LSC) and (La0.6Sr0.4)(0.98)FeO3- (LSF) was investigated by means of Electrical Conductivity Relaxation (ECR) in oxidizing atmospheres (0.2-0.1 bar pO(2)) from 650 degrees C to 900 degrees C. We observed reversible and reproducible changes in materials' performance as a consequence of thermal treatment, manifested through drastic changes in surface exchange coefficient (k(chem)) and the related activation energy with thermal history. The effect is found to be more pronounced in case of LSF, where k(chem) at 650 degrees C and 0.1 bar pO(2) can vary from 3 x 10(-4) to 1.1 x 10(-5) cm s(-1), while bulk properties such as electrical conductivity and the chemical diffusion coefficient of oxygen remain constant. The changes are related to a surface-confined phenomenon and the transition from one state to another is found to follow classical models of nucleation and growth processes. The findings demonstrate the importance of thermal history for studies of oxygen exchange kinetics in perovskite materials and offer an explanation for some of the discrepancies found in the literature.",
author = "Dordije Tripkovic and Rainer Kungas and Mogensen, {Mogens Bjerg} and Hendriksen, {Peter Vang}",
year = "2019",
doi = "10.1039/c9ta02607j",
language = "English",
volume = "7",
pages = "11782--11791",
journal = "Journal of Materials Chemistry A",
issn = "2050-7488",
publisher = "RSC Publications",
number = "19",

}

RIS

TY - JOUR

T1 - Surface recrystallization - an underestimated phenomenon affecting oxygen exchange activity

AU - Tripkovic, Dordije

AU - Kungas, Rainer

AU - Mogensen, Mogens Bjerg

AU - Hendriksen, Peter Vang

PY - 2019

Y1 - 2019

N2 - The rate of oxygen surface exchange on (La0.6Sr0.4)(0.99)CoO3- (LSC) and (La0.6Sr0.4)(0.98)FeO3- (LSF) was investigated by means of Electrical Conductivity Relaxation (ECR) in oxidizing atmospheres (0.2-0.1 bar pO(2)) from 650 degrees C to 900 degrees C. We observed reversible and reproducible changes in materials' performance as a consequence of thermal treatment, manifested through drastic changes in surface exchange coefficient (k(chem)) and the related activation energy with thermal history. The effect is found to be more pronounced in case of LSF, where k(chem) at 650 degrees C and 0.1 bar pO(2) can vary from 3 x 10(-4) to 1.1 x 10(-5) cm s(-1), while bulk properties such as electrical conductivity and the chemical diffusion coefficient of oxygen remain constant. The changes are related to a surface-confined phenomenon and the transition from one state to another is found to follow classical models of nucleation and growth processes. The findings demonstrate the importance of thermal history for studies of oxygen exchange kinetics in perovskite materials and offer an explanation for some of the discrepancies found in the literature.

AB - The rate of oxygen surface exchange on (La0.6Sr0.4)(0.99)CoO3- (LSC) and (La0.6Sr0.4)(0.98)FeO3- (LSF) was investigated by means of Electrical Conductivity Relaxation (ECR) in oxidizing atmospheres (0.2-0.1 bar pO(2)) from 650 degrees C to 900 degrees C. We observed reversible and reproducible changes in materials' performance as a consequence of thermal treatment, manifested through drastic changes in surface exchange coefficient (k(chem)) and the related activation energy with thermal history. The effect is found to be more pronounced in case of LSF, where k(chem) at 650 degrees C and 0.1 bar pO(2) can vary from 3 x 10(-4) to 1.1 x 10(-5) cm s(-1), while bulk properties such as electrical conductivity and the chemical diffusion coefficient of oxygen remain constant. The changes are related to a surface-confined phenomenon and the transition from one state to another is found to follow classical models of nucleation and growth processes. The findings demonstrate the importance of thermal history for studies of oxygen exchange kinetics in perovskite materials and offer an explanation for some of the discrepancies found in the literature.

U2 - 10.1039/c9ta02607j

DO - 10.1039/c9ta02607j

M3 - Journal article

VL - 7

SP - 11782

EP - 11791

JO - Journal of Materials Chemistry A

JF - Journal of Materials Chemistry A

SN - 2050-7488

IS - 19

ER -