NMR studies were carried out for ferroelectric NaNO2 particles embedded into molecular sieves MCM-41 and SBA-15 with various pore sizes. 23Na spin-lattice relaxation was measured within a large temperature range covering the ferroelectric phase transition in bulk sodium nitrite till sodium nitrite melting. Longitudinal nuclear magnetization restoration in the rigid confined sodium nitrite was found to be described well by the model of thermally activated random reorientations of the NO2 groups. The activation enthalpy of NO2 reorientations was evaluated above and below the ferroelectric phase transition in confined sodium nitrite. Its values were shown to be similar to that in bulk sodium nitrite.
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