Mechanism of proton transport in hexagonal ice

In polycrystalline samples of hexagonal ice both Bjerrum defect dynamics and translational diffusion of protons have been identified by deuteron nuclear magnetic resonance stimulated echo experiments. The temperature dependence of these processes in combination with literature data of tracer diffusion coefficients reveals that the material transport originates from interstitial mediated diffusion of intact water molecules. The jump length of the self-interstitials can be estimated to be 1.5 to 4 times the size of interstitial cages. The time scale associated with the slower component of this two-step mechanism contradicts (in parts) the standard interpretation of the dielectric Debye relaxation.