Relationship between supercooling stability and solution structure in sodium acetate aqueous solution

Abstract

We have observed the solution structure of the supercooled sodium acetate aqueous solution, especially for the existence of clusters and their crystallization process, by means of Scanning electron microscopy (SEM) with the freeze replica method. Microscopic internal structure of sodium acetate trihydrate crystals mainly constitutes the aggregates of 100–200nm in diameter, which consists of the clusters of 10–20nm in diameter. In the case of a supercooled aqueous solution of 293K, two types of aspect in the vitrified aqueous solution mainly exist: one is the clusters of 10–20nm in diameter; the other is the smooth zone without any structure. At 263K, the relationship among clusters of 10–20nm and their aggregates of 100–200nm was clearly observed. The aggregates construct the three-dimensional loose networks, which are not fully packed, different from the crystal.