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2 2015

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The MAS NMR study of solid solutions based on the YAG crystal

Padlyak B. V., Sergeev N. A., Olszewski M., Stępień P.

Nukleonika

2015

Vol. 60, No. 3, part 1

417--421

An 27Al magic angle spinning (MAS) nuclear magnetic resonance (NMR) study of nominally pure and Cr-doped yttrium-aluminum garnet (Y3Al5O12 and Y3Al5O12:Cr) crystals is reported. It has been shown that the doping by Cr of the Y3Al5O12 crystals leads to the variation of the occupation by Al atoms both octahedrally and tetrahedrally coordinated sites of the garnet lattice.

Dynamic of water molecules in natrolite

Paczwa M., Sergeev N. A., Olszewski M., Sapiga A. A., Sapiga A. V.

Journal of Education and Technical Sciences

2015

Vol. 2, nr 1

15--20

Molecular mobility of water molecules has been investigated in the natural zeolite natrolite (Na2Al2Si3O10 ·2H2O) by 1H NMR. Spin-lattice relaxation times in the laboratory and rotating frames (T1 and T1-) have been measured as a function of temperature for a polycrystalline sample. It has been shown that the spin-lattice relaxations times of 1H are governed by the translation motions of water molecules in the natrolite pores. 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 observed also. At low temperature (T < 250 K) the dipolar interaction with paramagnetic impurities (presumably with Fe3+ ions) become significant as a relaxation mechanism of 1H nuclei.