Can secondary nucleation exist in ice banding of freezing colloidal suspensions?

TL;DR

This study investigates whether secondary nucleation can explain ice banding in freezing colloidal suspensions, finding that the observed undercoolings do not support the secondary nucleation mechanism.

Contribution

The paper provides a quantitative examination that challenges the secondary nucleation theory as the mechanism behind ice banding in colloidal suspensions.

Findings

Interfacial undercooling measured does not meet nucleation undercooling requirements.

Secondary nucleation mechanism is disproved for ice banding.

Results suggest alternative mechanisms are responsible for ice banding.

Abstract

The formation mechanism of ice banding in the system of freezing colloidal suspensions, which is of significance in frost heaving, ice-templating porous materials and biological materials, still remains a mystery. Recently, the theory of secondary nucleation and growth of ice has been proposed to explain the emergence of a new ice lens. However, this theory has not been quantitatively examined. Here, we quantitatively measured the initial interfacial undercooling of a new ice lens and the nucleation undercoolings of suspensions. We found that the interfacial undercooling can not satisfy the nucleation undercooling of ice and hence disprove the secondary nucleation mechanism for ice banding.