A Mike Ward and Bart Kahr collaboration with Courant researchers Miranda Holmes-Cerfon and Robert Kohn is featured on the cover of PNAS (click here for the full article) and was picked up by NYU Research Highlights (click here). Postdoctoral fellow Ran Drori is the first author.
Significance: Freezing and melting of ice are one of the most common events on Earth. The dynamics of ice crystallization are relevant to climate research, mitigating frost damage in agriculture and construction, glacier dynamics, tissue and food preservation, and transportation. We describe the use of microfluidic devices, accompanied by precise temperature control, to examine the effect of H/D isotope exchange between liquid light water and solid heavy water on ice growth dynamics. These studies revealed unusual morphologies at the ice surface in contact with the liquid, including curious unsteady morphological features that give the appearance of oscillation due to complex interplay of H/D exchange, thermal gradients, and local surface curvature.
Abstract: The growth dynamics of D2O ice in liquid H2O in a microfluidic device were investigated between the melting points of D2O ice (3.8 °C) and H2O ice (0 °C). As the temperature was decreased at rates between 0.002 °C/s and 0.1 °C/s, the ice front advanced but retreated immediately upon cessation of cooling, regardless of the temperature. This is a consequence of the competition between diffusion of H2O into the D2O ice, which favors melting of the interface, and the driving force for growth supplied by cooling. Raman microscopy tracked H/D exchange across the solid H2O–solid D2O interface, with diffusion coefficients consistent with transport of intact H2O molecules at the D2O ice interface. At fixed temperatures below 3 °C, the D2O ice front melted continuously, but at temperatures near 0 °C a scalloped interface morphology appeared with convex and concave sections that cycled between growth and retreat. This behavior, not observed for D2O ice in contact with D2O liquid or H2O ice in contact with H2O liquid, reflects a complex set of cooperative phenomena, including H/D exchange across the solid–liquid interface, latent heat exchange, local thermal gradients, and the Gibbs–Thomson effect on the melting points of the convex and concave features.
This work was supported by the National Science Foundation's Materials Science & Engineering Center and the Department of Energy.