Organization of oxygen vacancies in low-temperature La/sub 2/Mo/sub 2/O/sub 9/ ion conductor

Recently, La ₂Mo ₂O ₉ has been presented as a promising electrolyte material for solid oxide fuel cells (SOFCs), and recent results from our group have confirmed that such compound fulfill some of the requirements for SOFCs applications such as a high ion conduction and a wide oxygen partial pressure range of pure ionic conduction. Nevertheless, the mechanism of oxygen conduction in La ₂Mo ₂O ₉ is still not understood, in particular some questions remain about the strong decrease of conductivity from the cubic high-temperature (HT) phase to the monoclinic low-temperature (LT) phase. In the present work, some nanocompositional and nanostructural features of the LT- La ₂Mo ₂O ₉ superstructure that could explain the low conductivity of the LT-phase are put into evidence.