Homogeneous Nucleation of Predominantly Cubic Ice Confined in Nanoporous Alumina

The nucleation mechanism of water can be precisely regulated by confinement within nanoporous alumina. We found a transition from heterogeneous nucleation of hexagonal ice (I-h). to homogeneous nucleation of predominantly cubic ice (I-c) with decreasing pore diameter. These results lead to a phase diagram of water under confinement. It contains a (stable) predominant I-c form) a form known to exist only in the upper atmosphere: Possible applications range from cryopreservation to construction materials like cement.