Effect of substitutional doping of tin in highly conductive barium iron vanadate glass

Vanadate glasses have numerous industrial applications and enhancement of their electrical conductivity is of interest for conducting glass for electronic and optical devices. The effect of substitutional doping of Sn${}^{IV}$ (4d${}^{10}$) for Fe${}^{III}$ on the local structure and electrical conductivity ($\sigma$) of barium iron vanadate glass is investigated in this study. The $\sigma$ value of as-cast 20BaO $\cdot$ 3SnO${}_2\cdot$ 7Fe${}_2$O${}_3\cdot$ 70V${}_2$O${}_5$ glass (5.9 $\times$ 10${}^{-7}$ S cm${}^{-1}$) is comparable to that of as-cast 20BaO $\cdot$ 10Fe${}_2$O${}_3\cdot$ 70V${}_2$O${}_5$ glass. The $\sigma$ value of the doped glass increases to 1.9 $\times$ 10${}^{-1}$ S cm${}^{-1}$ after isothermal annealing at 500°C for 15 min, which is an order of magnitude larger than that of the undoped glass annealed under the same conditions. From room-temperature Mössbauer spectra of conductive vanadate glasses annealed at 500°C for 15 min, it is demonstrated that the quadrupole splitting of the Fe${}^{III}$ (0.60 mm s${}^{-1}$) in 3 mol%-SnO${}_2$ containing vanadate glass is slightly smaller than that of SnO${}_2$-free vanadate glass (0.65 mm s${}^{-1}$). This indicates smaller distortion of FeO${}_4$ and VO${}_4$ tetrahedra in the SnO${}_2$-containing glass compared to the undoped glass, which is responsible for a marked increase in the carrier mobility. (© 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)