SPIN-LATTICE RELAXATIONS STUDY OF WATER MOBILITY IN NATURAL NATROLITE

zeolite NMR natrolite water mobility.

РЕЛЯТИВИСТСКИЕ ЭФФЕКТЫ В ОКСИДАХ И ГАЛОГЕНИДАХ ПЕРЕХОДНЫХ И ПОСТПЕРЕХОДНЫХ МЕТАЛЛОВ, PEROVSKITE SOLID SOLUTIONS — A MONTE CARLO STUDY OF THE DEEP EARTH ANALOGUE (K, Na)MgF3, ...

S.P. Gabuda on the occasion of his 80th birthday SPIN-LATTICE RELAXATIONS STUDY OF WATER MOBILITY IN NATURAL NATROLITE M. Paczwa1, A.A. Sapiga2, M. Olszewski1, N.A. Sergeev1, A.V. Sapiga2 2Physical-Technical Institute, V.I. Vernadsky Crimean Federal University, Simferopol, Russia Received August, 8, 2015 1Institute of Physics, University of Szczecin, Poland E-mail: sergeev@wmf.univ.szczecin.pl The mobility of water molecules in natural natrolite (Na2Al2Si3O10 2H2O) is investigated by the 1H NMR method. <...> The spin-lattice relaxation times in the laboratory and rotating frames (T1 and T1…) are measured as a function of the temperature for a polycrystalline sample. <...> From experimental T1 data it follows that at T > 286 K the diffusion of water molecules along channels parallel to the c axis is observed. <...> From experimental T1…data it follows that at T > 250 K the diffusion of water molecules in transversal channels of natrolite is also observed. <...> At a low temperature (T < 250 K) the dipolar interaction with paramagnetic impurities (presumably Fe3+ ions) becomes significant as a relaxation mechanism of 1H nuclei. <...> Careful refinements of the natrolite structure were carried out by X-ray and neutron diffraction [ 2— 5 ]. <...> The natrolite framework consists of chains of AlO4 and SiO4 tetrahedra linked together via common oxygen atoms. <...> The natrolite structure contains channels running parallel to the c axis (Fig. 1, a). <...> Channels are connected with each other by oxygen windows (Fig. 1, b). <...> Natrolite structure: projected on the (001) plane (a); natrolite chains and windows from oxygen ions (b) Paczwa M., Sapiga A.A., Olszewski M., Sergeev N.A., Sapiga A.V., 2016 336 M. PACZWA, A.A. SAPIGA, M. OLSZEWSKI ET AL. <...> The solid lines are electrostatic bonds between water oxygen atoms and sodium ions. <...> Water molecules and sodium ions form zigzag chains along the channel parallel to the c axis. <...> Water molecules occupy two sites in the channels and the other sites are occupied by sodium ions. <...> Each water molecule is coordinated by two framework oxygen atoms and by two sodium ions (Fig. 2). <...> The diameter of oxygen windows in the [110] direction is 2.60 Е, and the diameter of channel parallel to the c <...>

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