Ferroelectricity and gradual melting in NaNO2 particles confined within porous alumina

Abstract

NMR and dielectric studies were carried out for ferroelectric NaNO2 embedded into porous alumina. 23Na spin-lattice relaxation and static lineshape were measured within a large temperature range covering the ferroelectric phase transition in bulk sodium nitrite till NaNO2 melting. The coexistence of the crystalline and melted states of confined sodium nitrite was observed above 400 K, gradual melting being over at about 510 K. The solid portion of confined sodium nitrite bore ferroelectricity with phase transition temperature higher than that in bulk NaNO2. Correlation time of molecular mobility in the melted fraction was found and activation enthalpy was estimated. © 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.