Proton mobility in Ruddlesden–Popper phase H2La2Ti3O10 studied by 1H NMR

Abstract

To study protons localization in H1.83K0.17La2Ti3O10·0.17H2O and their motional characteristics, complementary Nuclear Magnetic Resonance (NMR) techniques have been applied. 1H Magic Angle Spinning NMR evidences the presence of different proton containing species. By analyzing the temperature dependence of the 1H MAS NMR spectrum we attribute the observed lines to interlayer H+ in regular sites (isolated and in water rich environment), water protons and protons from various defects. The temperature behaviors of the spectral lines intensities and widths point out that intercalated water molecules are involved in translational motion that is confirmed by spin lattice relaxation rate (R1) and spin-lattice relaxation rate in rotating frame (R1ρ) measurements. It has been shown that for a correct determination of the proton motional parameters the Kohlrausch-Williams-Watts correlation function must be used. Its application results in the following parameters of proton motion in the interlayer space of H1.83K0.17La2Ti3O10·0.17H2O: Ea = 0.194(2) eV, β = 0.28(1), τ0=6.2(1)×10−10 s.