Fast oxygen exchange and diffusion kinetics of grain boundaries in Sr-doped LaMnO3 thin films

被引：102
作者：
Navickas, Edvinas [1 ]
Huber, Tobias M. [1 ]
Chen, Yan [2 ]
Hetaba, Walid [3 ]
Holzlechner, Gerald [1 ]
Rupp, Ghislain [1 ]
Stoeger-Pollach, Michael [3 ]
Friedbacher, Gernot [1 ]
Hutter, Herbert [1 ]
Yildiz, Bilge [2 ]
Fleig, Juergen [1 ]
机构：
[1] Vienna Univ Technol, Inst Chem Technol & Analyt, A-1060 Vienna, Austria
[2] MIT, Dept Nucl Sci & Engn, Cambridge, MA 02139 USA
[3] Vienna Univ Technol, Univ Serv Ctr Transmiss Elect Microscopy, A-1040 Vienna, Austria
来源：
PHYSICAL CHEMISTRY CHEMICAL PHYSICS | 2015年 / 17卷 / 12期
基金：
奥地利科学基金会;
关键词：
FUEL-CELL CATHODES; SURFACE EXCHANGE; TRACER DIFFUSION; REDUCTION; INTERFACE; CHEMISTRY; TRANSPORT; SITES; LAYER; SIMS;
D O I：
10.1039/c4cp05421k
中图分类号：
O64 [物理化学（理论化学）、化学物理学];
学科分类号：
070304 ; 081704 ;
摘要：
In this study, the contribution of grain boundaries to the oxygen reduction and diffusion kinetics of La0.8Sr0.2MnO3 (LSM) thin films is investigated. Polycrystalline LSM thin films with columnar grains of different grain sizes as well as epitaxial thin films were prepared by pulsed laser deposition. O-18 tracer exchange experiments were performed at temperatures from 570 degrees C to 810 degrees C and subsequently analyzed by secondary ion mass spectrometry (SIMS). The isotope concentration depth profiles of polycrystalline films clearly indicate contributions from diffusion and surface exchange in grains as well as in grain boundaries. Measured depth profiles were analyzed by finite element modeling and revealed the diffusion coefficients D and oxygen exchange coefficients k of both the grain bulk and grain boundaries. Values obtained for grain boundaries (D-gb and k(gb)) are almost three orders of magnitude higher than those of the grains (D-g and k(g)). Hence, grain boundaries may not only facilitate fast oxygen diffusion but also fast oxygen exchange kinetics. Variation of the A-site stoichiometry ((La0.8Sr0.2)(0.95)MnO3) did not lead to large changes of the kinetic parameters. Properties found for epitaxial layers without grain boundaries (D-b and k(b)) are close to those of the grains in polycrystalline layers.
引用
收藏
页码：7659 / 7669
页数：11
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