Stability of Cubic Ice in Mesopores

We examined the effect of pore geometry on the stability of cubic ice in mesopores by measuring the change of the X-ray diffraction pattern for ice confined in cylindrical, interconnected cylindrical, interconnected spherical, and interconnected irregular pores of silica during a heating process. The results obtained clearly indicated that the stability of cubic ice in the mesopores depends on the pore geometry. Cubic ice confined to the interconnected spherical cavities of KIT-5 is metastable with respect to hexagonal ice, similar to bulk cubic ice. On the other hand, cubic ice confined to the cylindrical and interconnected cylindrical pores of SBA-15 and KIT-6 is stable up to the melting point of the ice, in accord with previous studies.