Fig. 7: Evolution of spherulites towards more stable phases.
From: Controlled spherulitic crystal growth from salt mixtures
a Raman spectra of late-stage evolution of spherulites in a xMg = 0.12 droplet under slow evaporation conditions (RH ≥ 60%). These measurements reveal that the initial spherulites correspond to phase III, bladed crystals formed on the spherulites originate from an unidentified phase, and the final polyaggregates recrystallize into phase V after complete dehydration. The spectra are accompanied by reference spectra of Na2SO4 phase III and phase V (shown in black). b Scanning electron microscopy image of a spherulitic polyaggregate after complete dehydration at RH = 63%. The white arrow highlights the growth history of a blade that developed from the spherulite. c Magnification of boxed area in (b); In this later stage spherulite the nanocrystals, as shown in Fig. 3b, coalesced into more stable finger-like structures. The corresponding EDX elemental map (left) confirms that the the fused structures consist of sodium sulfate.
