Affiliation: | Department of Metallurgy and Materials Science, University of Toronto, Toronto, Ontario, M5S 1A4, Canada Department of Energy Mines and Resources, CANMET, 555 Booth Street, Ottawa, Ontario K1A 0G1, Canada AECL Research, Chalk River, Ontario K0J 1J0, Canada |
Abstract: | The ionic conductivity of the bulk phase of bonded hydronium NASICON (HyceramTM) was measured at equilibrium with an H2O/N2 and then a D2O/N2 atmosphere, each at 100% relative humidity and 75% relative humidity over the temperature range 25°C to 50°C. At 100% relative humidity and 25°C, the protonic system had a bulk conductivity of 5.0×10−4 S/cm and an activation energy of 17.3kJ/mole; the same sample, when deuterated, had a bulk conductivity of 2.2×10−4 S/cm and an activation energy of 19.3kJ/mole. At 75% relative humidity and 25°C, the conductivity of the protonated system decreased to 1.4×10−4S/cm with an activation energy of 24.1 kJ/mole. The deuterated sample at 75% relative humidity had a bulk conductivity of 5.4×10−5 S/cm with an activation energy of 26.0 kJ/mole. The isotope effect suggested a proton hopping (Grotthus) mechanism as the means by which the protons pass through the lattice. |