To lower operating temperatures of solid oxide fuel cells (SOFCs), the development of ion-conducting oxides with high conductivity and durability is desired. In this work, we investigated Zr-substituted “Ba₃Y₄O₉” as an ionic conductor at intermediate temperatures and found that the Zr substitution for Y dramatically improves the phase stability in humidified atmospheres at 300–800 °C. The total electrical conductivity of nominally 20 mol% Zr-substituted Ba₃Y₄O₉ sample is about 0.1 mS/cm at 500 °C in both dry H₂ and O₂ atmospheres. Because an increase in the conductivity in a humidified atmosphere was not observed, the conducting carriers may be oxygen ions. Besides, in the Zr-substituted “Ba₃Y₄O₉” samples, we observed that BaO-rich phase coexists with the main phase whose composition is estimated to be Ba:(Y + Zr) ~ 2:3. Therefore, the main conducting phase might be Ba-deficient Ba₃Y₄O₉. The mechanism of the ionic conduction and the improvement of chemical stability has not been revealed yet due to the lack of crystallographic information about the Ba-deficient phase. While we are now working on further investigation, we promptly report the characteristic of the new compound.

为了降低固体氧化物燃料电池（SOFC）的工作温度，需要开发具有高导电性和耐久性的离子导电氧化物。在这项工作中，我们在中等温度下研究了 Zr 取代的“Ba ₃ Y ₄ O ₉ ”作为离子导体，发现 Zr 取代 Y 显着提高了 300-800°C 潮湿环境中的相稳定性。标称 20 mol% Zr 取代的 Ba ₃ Y ₄ O ₉样品的总电导率在 500 °C 下在干燥的 H ₂和 O _{2 中}约为 0.1 mS/cm气氛。因为在潮湿的气氛中没有观察到电导率的增加，所以导电载体可能是氧离子。此外，在 Zr 取代的“Ba ₃ Y ₄ O ₉ ”样品中，我们观察到富含 BaO 的相与主相共存，其组成估计为 Ba:(Y + Zr) ~ 2:3。因此，主导电相可能是缺Ba的Ba ₃ Y ₄ O ₉。由于缺乏关于 Ba 缺相的晶体学信息，离子传导的机制和化学稳定性的提高尚未揭示。在我们正在进行进一步调查的同时，我们及时报告了新化合物的特征。