The study of hydronium NASICON conductivity with deuterium

Abstract The ionic conductivity of the bulk phase of bonded hydronium NASICON (Hyceram TM ) was measured at equilibrium with an H 2 O/N 2 and then a D 2 O/N 2 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 17.3 kJ mole ; the same sample, when deuterated, had a bulk conductivity of 2.2×10 −4 S cm and an activation energy of 19.3 kJ mole . At 75% relative humidity and 25°C, the conductivity of the protonated system decreased to 1.4×10 −4 S 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.