1H NMR study of the hydrogen dynamics in the (NaS)xGe(OH)4-x•yH2O ceramic proton conductors

H-1 NMR was performed on the ceramic proton conductor (NaS)(x)Ge(OH)(4-x)center dot yH(2)O for x = 2, 3 and y-1-4 over the temperature range of -100 degrees C to 400 degrees C. NMR spectra, nuclear spin-lattice relaxation rates (R-1), spin-spin relaxation rates (R-2), and rotating frame relaxation rates (R-1p) were obtained for both hydrated and dehydrated samples. It was found that the low temperature NMR spectra were consistent with simulated H2O lineshapes, and the presence of H3O+ at low temperature was not detected within the experimental uncertainty. Short- and long-range hydrogen motion occurred together, a signature of Grotthuss conduction mechanisms. The long range motion was a combination of H+ and H2O diffusion, with H2O motion limiting H+ dynamics as the onset temperature was approached. (C) 2012 Elsevier B.V. All rights reserved.