The dynamics of surface exchange reaction in oxygen permeable ceramics and its controlling factors

2019 Fiscal Year Final Research Report

• Project/Area Number: 17H03391
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: Inorganic materials/Physical properties
• Research Institution: Nagoya Institute of Technology
• Principal Investigator: Kagomiya Isao 名古屋工業大学, 工学(系)研究科(研究院), 准教授 (40318811)
• Co-Investigator(Kenkyū-buntansha): 松田 巌 東京大学, 物性研究所, 准教授 (00343103)
• Project Period (FY): 2017-04-01 – 2020-03-31
• Keywords: 混合導電性セラミックス

Outline of Final Research Achievements

This study investigated systematic relation between oxygen permeation flux JO2 and Ca content in La1-xCaxFeO3-d(LCF). The x=0.35 sample showed the highest JO2 in the LCF. The ion conductivity and surface exchange reaction of x=0.35 sample was obtained by simultaneous investigation of the oxygen permeation flux and oxygen chemical potential on the sample surface.
JO2 of x=0.35 at 800 and 850 ℃ was found to be limited by surface exchange reaction on the low oxygen partial pressure side. The rate-determining step for the surface exchange reaction is charge transfer relating to O2 molecule desorption, resulting from the lower hole(Fe4+) concentration on the low oxygen partial pressure side under the reduction condition. The increase in hole concentration under the reduction condition is a possible strategy to improve the surface exchange reaction.

Free Research Field

無機物性

Academic Significance and Societal Importance of the Research Achievements

本研究では、La1-xCaxFeO3-d(LCF)について系統的に調べることで、ある特定の組成領域(x=0.3-0.4)で高い酸素透過性を示すことを見出した。この結果は高い酸素透過性に寄与すると考えられてきたSr,Coを含有しなくとも、学術的な観点から、格子自由体積、酸素欠陥量を制御することで透過性向上が可能であることを示したものである。この系では800℃以下では表面交換反応が律速となるが、この律速要因を突き止め、これより今後の表面交換反応の速い酸素透過性セラミックスの開発のために有効な学術指針を提供することができた。