Dielectric and NMR studies of nanoporous matrices loaded with sodium nitrite

The generalized Jonscher's relationship for conductivity and its confirmation for porous structures

“…A possibility to produce a large amount of these nanocomposite materials (NCM) permits to use additional experimental methods such as neutron diffraction, measurements of heat capacity, internal friction and shear modulus, NMR for obtaining the information about micro-and macroscopic peculiarities of properties and structure of NCM. During last years the similar studies have been carried out for sodium nitrite embedded into opals [14], porous glasses [15][16][17][18][19][20][21][22], chrysotile asbestos [23] and mesoporous structures MCM-41 and SBA-15 [24]. For these NCM it was found the giant growth of dielectric permittivity at low frequencies [18] and essential increasing of conductivity in the paraelectric phase [22,25], the change of type of phase transition (PT) from the first-order PT to the second-order one at NaNO 2 nanocluster size smaller than 50 nm [15,21,26].…”

Ferroelectric phase transitions in sodium nitrite nanocomposites

“…Due to high wetting ability it is possible to produce nanocomposite sodium nitrite on the basis of different porous media with various topology and dimensionality: 3D random dendritetype (porous glasses) and regular (opals) interconnected nanocaverns, quasi-1D parallel nanochannels (chrysotile asbestos and mobile crystalline material (MCM)-41) etc. Such nanocomposites have been extensively studied by different experimental methods including calorimetry [1], nuclear magnetic resonance (NMR) [2][3][4], ultrasonic [5,6] and dielectric [3,[7][8][9][10] measurements, Raman [11], X-ray and neutron diffraction [12][13][14][15] etc, and very intriguing and surprising results were obtained. In particular it was shown that sodium nitrite (NaNO 2 ) within artificial opals demonstrates a giant growth of ε (up to 10 8 at 100 Hz) at approaching the bulk melting temperature [7].…”

Dielectric and calorimetric investigations of KNO3 in pores of nanoporous silica matrices MCM-41

“…The polar properties of nanocomposite structures based on porous matrices have not been adequately investi gated. The majority of publications have been devoted to the study of small particles of sodium nitrite in pores of synthetic opals, porous glasses, and molecular sieves MCM 41 and SBA 15 (see [1][2][3][4][5][6][7] and refer ences therein). There are few works [8][9][10][11][12] concerned with the study of Rochelle salt and triglycine sulfate in Al 2 O 3 porous films and molecular sieves.…”