电导率
化学
氧化物
中子衍射
分析化学(期刊)
离子
兴奋剂
电解质
质子
电阻率和电导率
无机化学
物理化学
结晶学
材料科学
晶体结构
电极
工程类
物理
电气工程
有机化学
量子力学
光电子学
色谱法
作者
Yuki Suzuki,Taito Murakami,Kotaro Fujii,James Hester,Yuta Yasui,Masatomo Yashima
出处
期刊:Inorganic Chemistry
[American Chemical Society]
日期:2022-05-03
卷期号:61 (19): 7537-7545
被引量:14
标识
DOI:10.1021/acs.inorgchem.2c00671
摘要
Hexagonal perovskite-related oxides have garnered a great deal of research interest because of their high oxide-ion conductivity at intermediate temperatures, with Ba7Nb4MoO20 being a notable example. However, concomitant proton conduction in Ba7Nb4MoO20 may cause a decrease in power efficiency when used as the electrolyte in conventional solid oxide fuel cells. Here, through investigations of the transport and structural properties of Ba7Nb4-xWxMoO20+x/2 (x = 0-0.25), we show that the aliovalent substitution of Nb5+ by W6+ not only increases the oxide-ion conductivity but also dramatically lowers proton conductivity. The highest conductivity is achieved for x = 0.15 composition, with 2.2 × 10-2 S cm-1 at 600 °C, 2.2 times higher than that of pristine Ba7Nb4MoO20. The proton transport number of Ba7Nb3.85W0.15MoO20.075 is smaller compared with Ba7Nb4MoO20, Ba7Nb3.9Mo1.1O20.05, and Ba7Ta3.7Mo1.3O20.15. The structure analyses of neutron diffraction data of Ba7Nb3.85W0.15MoO20.075 at 25 and 800 °C reveal that the aliovalent W6+ doping introduces interstitial oxide ions in the intrinsically oxygen-deficient c' layers, thereby simultaneously increasing the carrier concentration for oxide-ion conduction and decreasing oxygen vacancies responsible for dissociative absorption of water. Neutron scattering length density distribution was examined using the maximum-entropy method and neutron diffraction data at 800 °C, which indicates the interstitialcy oxide-ion diffusion in the c' layers of Ba7Nb3.85W0.15MoO20.075. Ba7Nb3.85W0.15MoO20.075 exhibits extremely high chemical and electrical stability in the wide oxygen partial pressure P(O2) region [ex. 10-23 ≤ P(O2) ≤ 1 atm at 903 °C]. The present results offer a strategy for developing pure oxide-ion conducting hexagonal perovskite-related oxides for possible industrial applications.
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