Physica status solidi. C vol:4 issue:3 pages:757-760
Temperature-dependent Raman study of NaNO2 confined within porous glass with a pore size of 46 nm has been performed. It is demonstrated that the bandwidths and frequencies of the Raman bands as a function of temperature show similar behaviour, but not identical, as those observed for bulk NaNO2. This result indicates that the first-order phase transition mechanism is only slightly modified by embedding
NaNO2 into the porous glass. It seems that formation of “premelted state” is not significant in the studied
material, at least up to 40-50 K above Tc. At higher temperatures, however, a significant increase of bandwidth of the 1326 cm–1 band is observed, which could indicate appearance of “premelted” state. The dielectric measurements are consistent with this view since they show large increase of dielectric permittivity above 480 K, well below the NaNO2 melting temperature (554 K).