Oxygen-ion and proton transport in Ba4Na2W2O11

The perovskite-related tungstate of Ba4Na2W2O11 with oxygen deficiency was studied by X-ray powder diffraction, IR-spectroscopy, electrical conductivity measurements and thermogravimetry. Electrical conductivity and transport numbers were measured with varying T in dry (pH2O = 10− 4.5 atm) and wet (pH2O = 1.92·10− 2 atm) atmospheres. This phase is capable of dissociative dissolution of water and can exhibit proton transport below 500 °C. The localization of protons on oxygen results in the appearance of OH− groups, and a small fraction of protons is present in the form of H3O+-ions.