High proton conductivity in porous P2O5-SiO2 glasses

High proton conducting P2O5-SiO2 glasses were prepared using the sol-gel me thod, the electrical conductivities of which were studied in relation to th e pore structure and the adsorbed water. The pore properties of SiO2 and P2 O5-SiO2 glasses were controlled by addition of formamide during the gel syn thesis, the specific surface areas of which were changed from 200 to 900 m( 2)/g-glass. These glasses absorb water molecules on exposure to a humid atm osphere. The conductivity increased with increasing logarithm of water conc entration and reached a saturated value above the water vapor pressure of 0 .8. The highest conductivity, 2 x 10(-2) S/cm at room temperature, was achi eved by 5P(2)O(5)-95SiO(2) glass heated at 700 degrees C and absorbing the water molecules.