1H NMR study of the hydrogen dynamics in the (NaS)xGe(OH)4-x*y H2O ceramic proton conductors
Journal article, 2012
1H NMR was performed on the ceramic proton conductor (NaS)xGe(OH)4-x*y H2O for x=2,3 and y≈1-4 over the temperature range of −100 °C to 400 °C. NMR spectra, nuclear spin-lattice relaxation rates (R1), spin-spin relaxation rates (R2), and rotating frame relaxation rates (R1ρ) 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.