Grain boundary ridge on sintered bonds between ice crystals

Abstract

Well-sintered snow examined in a scanning electron microscope revealed a newly observed morphological structure that protrudes into the pore space along ice grain boundaries. We have termed this a "grain boundary ridge." Grain boundary diffusion is a sintering process that occurs at the interface of two crystals, whereby mass migrates from the center of the contact to the surface of the bond. Since mass tends to sublimate from sharp features toward smaller curvature surfaces through vapor diffusion, a ridge developed by grain boundary diffusion will readily sacrifice mass to the surrounding ice surfaces. A mass balance between vapor and grain boundary diffusion based on the observed geometry is considered. This analysis indicates grain boundary diffusion may play a far more significant role than generally acknowledged. While this study was restricted to ice, it may have implications for other crystalline materials. © 2001 American Institute of Physics.