New Good Ionic Conductor: Ba-Deficient Ba3Y4O9 with Zr Substitution

18 December 2020, Version 1
This content is a preprint and has not undergone peer review at the time of posting.


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 20 mol% Zr-substituted Ba3Y4O9 is about 1 mS/cm at 700 °C in dry H­2 and O2 atmospheres and the contribution of electronic conduction (both hole and electron) is relatively small compared with Y-doped BaZrO3 (BZY) and Gd-doped CeO­­2 (GDC) which are typical intermediate-temperature ionic conductors. Besides, in the Zr-substituted “Ba3Y4O9” samples, we observed that BaO-rich amorphous 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.


fuel cells
oxygen ion conductor


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