Yashima Masatomo, Tsujiguchi Takafumi, Sakuda Yuichi, Yasui Yuta, Zhou Yu, Fujii Kotaro, Torii Shuki, Kamiyama Takashi, Skinner Stephen J
Department of Chemistry, School of Science, Tokyo Institute of Technology, 2-12-1 W4-17 O-okayama, Meguro-ku, Tokyo, 152-8551, Japan.
Department of Materials, Imperial College London, Exhibition Road, London, SW7 2AZ, UK.
Nat Commun. 2021 Jan 25;12(1):556. doi: 10.1038/s41467-020-20859-w.
Oxide-ion conductors are important in various applications such as solid-oxide fuel cells. Although zirconia-based materials are widely utilized, there remains a strong motivation to discover electrolyte materials with higher conductivity that lowers the working temperature of fuel cells, reducing cost. Oxide-ion conductors with hexagonal perovskite related structures are rare. Herein, we report oxide-ion conductors based on a hexagonal perovskite-related oxide BaNbMoO. BaNbMoO shows a wide stability range and predominantly oxide-ion conduction in an oxygen partial pressure range from 2 × 10 to 1 atm at 600 °C. Surprisingly, bulk conductivity of BaNbMoO, 5.8 × 10 S cm, is remarkably high at 310 °C, and higher than BiO- and zirconia-based materials. The high conductivity of BaNbMoO is attributable to the interstitial-O5 oxygen site, providing two-dimensional oxide-ion O1-O5 interstitialcy diffusion through lattice-O1 and interstitial-O5 sites in the oxygen-deficient layer, and low activation energy for oxide-ion conductivity. Present findings demonstrate the ability of hexagonal perovskite related oxides as superior oxide-ion conductors.
氧化物离子导体在诸如固体氧化物燃料电池等各种应用中都很重要。尽管基于氧化锆的材料被广泛使用，但人们仍有强烈的动机去发现具有更高电导率的电解质材料，以降低燃料电池的工作温度，从而降低成本。具有六方钙钛矿相关结构的氧化物离子导体很少见。在此，我们报道了基于六方钙钛矿相关氧化物BaNbMoO的氧化物离子导体。BaNbMoO显示出较宽的稳定范围，并且在600°C下，在2×10至1个大气压的氧分压范围内主要表现为氧化物离子传导。令人惊讶的是，BaNbMoO在310°C时的体电导率为5.8×10 S cm，非常高，且高于基于BiO和氧化锆的材料。BaNbMoO的高电导率归因于间隙-O5氧位点，它通过缺氧层中的晶格-O1和间隙-O5位点提供二维氧化物离子O1-O5间隙扩散，并且氧化物离子传导的活化能较低。目前的研究结果证明了六方钙钛矿相关氧化物作为优质氧化物离子导体的能力。
