Crossover from lamellar to spongy ice morphologies within a single ice crystal during unidirectional freezing of an aqueous solution

TL;DR

This study demonstrates, for the first time, a crossover from lamellar to spongy ice morphologies within a single ice crystal during unidirectional freezing of an aqueous solution, enhancing understanding of ice pattern formation.

Contribution

It reveals the in situ transition from lamellar to spongy ice in a single crystal, distinct from bi-crystal growth, providing new insights into ice pattern formation during unidirectional freezing.

Findings

Observed crossover from lamellar to spongy ice in a single crystal.

Identified spongy morphology as originating from intersecting tilted lamellar ice.

Provided a physical model for ice pattern formation in unidirectional freezing.

Abstract

Ice growth from liquid phase has been extensively investigated in various conditions, especially for ice freely grown in undercooled water and aqueous solutions. Although unidirectional ice growth plays a significant role in sea ice and freeze casting, the detailed pattern formation of unidirectionally grown ice in an aqueous solution remains elusive. For the first time, we in situ proved a crossover from lamellar to spongy ice morphologies of a single ice crystal via unidirectional freezing of an aqueous solution. The spongy ice morphology originates from the intersect of tilted lamellar ice and is observed in a single ice crystal, which is intrinsically different from the competitive growth of bi-crystal composed of two differently orientated grains in directional solidification. These results provide a complete physical picture of unidirectionally grown ice from aqueous solution and are believed to promote our understanding of various pattern of ice in many relevant domains where pattern formation of ice crystal is vital.