Equilibrium shape of ice Ih and roughening transition of prism facet

本文研究了冰在高压下沿着融化曲线的平衡形状。在-15℃和1600 bar下，平衡形状由圆盘状转变为六方片状。这表示在该点处的棱镜面上发生了粗糙化过渡。然而，生长和熔化的形状表现出六方各向异性的粗糙点附近，而平衡形状是圆形和各向同性的。此外，它们的六边形取向旋转了30°。我们还测量了冰在水中既不生长也不融化的融化曲线，结果表明，在-15℃和1600 bar时，融化曲线上有一个不连续点。粗糙点和不连续点吻合良好。这是令人困惑的，因为粗糙化转变是二级相变，对熔化曲线没有影响。如果不连续性与粗糙化无关，则其可归因于冰或水中的某些相变，而不是冰/水界面中的粗糙化。

We have investigated equilibrium shape of ice Ih along the melting curve under high pressures. The equilibrium shape showed phase transition from a circular disk to a hexagonal plate at -15℃ and 1600 bar. This represents that roughening transition occurred on prism facets at the point. However, growth and melting shapes exhibited hexagonal anisotropy near the roughening point, whereas equilibrium shape was circular and isotropic. In addition, their hexagonal orientations were rotated by 30°. Three shapes were different near the roughening point.We also have measured the melting curve on which ice neither grows nor melts in water ; as a result, there was a discontinuity on the melting curve at -15℃ and 1600 bar. The roughening and discontinuity points agree well. This is puzzling, because roughening transition is the second-order phase transition and affects nothing on the melting curve. If the discontinuity has no relation with roughening, it can be attributable to some phase transition in ice or water, not in an ice/water interface for roughening.