Resistometric and H nuclear magnetic resonance techniques were used to investigate the ion-exchanged layered perovskite at 90 to 350K. Compounds were synthesized by using the sol-gel method, and were then calcined at 650C. Analysis of the nuclear magnetic resonance data yielded activation energies, for proton motion, which ranged from 0.14 to 0.40eV and depended upon the water content. The frequency and temperature dependences of the proton spin-lattice relaxation times showed that the motion of the water molecules was essentially 2-dimensional. This reflected the layered structure of the material. A 1H line-narrowing transition and a single spin-lattice relaxation rate maximum were consistent with a Grotthuss-like mechanism for proton diffusion.

NMR and Conductivity Study of the Protonic Conductor, HPb2Nb3O10. C.E.Tambelli, J.P.Donoso, C.J.Magon, A.C.D.Angelo, A.O.Florentino, M.J.Saeki: Solid State Ionics, 2000, 136-137, 243-7