Investigations were made of high-temperature proton conduction in the tetragonal tungsten bronze niobates, Ba0.6Mg0.067Nb0.933O3. For all of the samples, the conductivities in dry N2 were higher than those in dry O2; indicating that these materials exhibited n-type electronic conduction. In wet atmospheres, the conductivities of the Ba-containing systems were higher than those in dry atmospheres; indicating the occurrence of proton conduction. The conductivities were low (σ600C ≈ 2 x 10−6 and 6 x 10−6S/cm in wet O2 and N2, respectively). Attempts to vary the Mg/Nb ratio, so as to increase the oxide-ion vacancy concentration and improve the proton conduction, were unsuccessful.

Investigation of Proton Conduction in the Tetragonal Tungsten Bronze Niobates - A0.6(M,Nb)O3 (A = Sr, Ba; M = Mg, Ti). E.Kendrick, M.S.Islam, P.R.Slater: Solid State Ionics, 2005, 176[39-40], 2975-8