Ionic conductivity in nanoporous composites SiO2/AgI

In this work, porous silicate glasses were mixed with an ionic conductor AgI to obtain SiO2/AgI composites. The porous glasses were either commercial Vycor glass (VPG) from Corning or synthesised from phase separated SiO2–B2O3–Na2O glasses. Depending upon the elaboration process, glasses with different pore sizes were obtained (4, 20 and 40 nm). Composites comprising different amounts of AgI were prepared by heating above the melting point of AgI. SEM characterisation of the obtained composites indicated that heat treatment induced an increase in the pore sizes. The conductivity of the composites was measured by impedance spectroscopy. The maximum conductivity, twice as large as that of pure AgI, was obtained for the 50AgI/50VPG composite, i.e. that comprising the glasses with the smallest pores.