Hydration and proton transport in solid solutions based on Ba2CaWO6

Hydrated alkaline-earth metal tungstates Ba4Ca2 + xW2 − xO12 − 2x with perovskite structure were studied by the thermogravimetry, 1H NMR, IR, and Raman spectroscopy methods. Electrical conductivity and transfer numbers were measured with varying T, \( p_{O_2 } \) and \( p_{H_2 O} \). The solid solutions are capable of reversibly intercalating water and can exhibit high-temperature proton transport. The localization of protons on oxygen results in the appearance of energetically nonequivalent OH groups; a small fraction of protons are present in the form of H2O and H3O+.