The sol–gel method was used to prepare glasses having high proton conductivities and chemical stability. The glasses were porous, with average pore diameters of less than 2nm, and 4nm, for glasses prepared by using PO(OCH3)3 and H3PO4, respectively. The P ions, which occurred as PO(OH)3 in TiO2-free glass, were polymerized with one or two bridging-O ions per PO4 unit with increasing TiO2 content. Although the P2O5–SiO2 binary glasses exhibited high conductivities (~10-2S/cm) at room temperature, they also dissolved after 24h immersion in water. The chemical stability of the glasses increased significantly upon adding TiO2.

Proton Conductivity in Sol–Gel-Derived P2O5–TiO2–SiO2 Glasses. M.Nogami, M.Suwa, T.Kasuga: Solid State Ionics, 2004, 166[1-2], 39-43