Crystal templating through liquid-liquid phase separation.

Controlled induction of crystal nucleation is a highly desirable but elusive goal. Attempts to speed up crystallization, such as high super saturation or working near a liquid-liquid critical point, always led to irregular and uncontrollable crystal growth. Here, we show that under highly nonequilibrium conditions of spinodal decomposition, water crystals grow as thin wires in a template-less formation of "Haareis". This suggests that such nonequilibrium conditions may be employed more widely as mechanisms for crystal growth control.