Roughening transition of prism faces of ice crystals grown from melt under pressure

By observing the crystal shapes and kinetics of ice Ih growing at high pressures from the melt, it was found that the prism f1 0 1̄ 0g faces undergo a roughening transition at approximately 16 C and 160MPa (1600 bar) in H2O ice, and 14 C and 180MPa (1800 bar) in D2O ice. At temperatures above the roughening transition, the prism facets completely vanished and the curves of growth rate versus growth drive were linear. In contrast, below the roughening temperature, regions of prism facets existed and the growth rate curves were approximately quadratic. The basal f0 0 0 1g faces persisted up to 0 C and gave approximately quadratic growth rate curves. The melting curves of ice Ih for H2O and D2O were accurately measured by direct observations of the solid–liquid coexistence equilibrium and found to agree with previous results obtained with other methods. r 2004 Elsevier B.V. All rights reserved. PACS: 64.90.+b; 68.35.Ct; 81.10.Aj; 81.30.Dz