Phase behaviors of deeply supercooled bilayer water unseen in bulk water

Toshihiro Kaneko, Jaeil Bai, Takuma Akimoto, Joseph S. Francisco, Kenji Yasuoka, Xiao Cheng Zeng

Research output: Contribution to journalArticlepeer-review

14 Citations (Scopus)


Akin to bulk water, water confined to an isolated nanoslit can show a wealth of new 2D phases of ice and amorphous ice, as well as unusual phase behavior. Indeed, 2D water phases, such as bilayer hexagonal ice and monolayer square ice, have been detected in the laboratory, confirming earlier computational predictions. Herein, we report theoretical evidence of a hitherto unreported state, namely, bilayer very low density amorphous ice (BL-VLDA), as well as evidence of a strong first-order transition between BL-VLDA and the BL amorphous ice (BL-A), and a weak first-order transition between BL-VLDA and the BL very low density liquid (BL-VLDL) water. The diffusivity of BL-VLDA is typically in the range of 10−9 cm2/s to 10−10 cm2/s. Similar to bulk (3D) water, 2D water can exhibit two forms of liquid in the deeply supercooled state. However, unlike supercooled bulk water, for which the two forms of liquid can coexist and merge into one at a critical point, the 2D BL-VLDL and BL high-density liquid (BL-HDL) phases are separated by the highly stable solid phase of BL-A whose melting line exhibits the isochore end point (IEP) near 220 K in the temperature−pressure diagram. Above the IEP temperature, BL-VLDL and BL-HDL are indistinguishable. At negative pressures, the metastable BL-VLDL exhibits a spatially and temporally heterogeneous structure induced by dynamic changes in the nanodomains, a feature much less pronounced in the BL-HDL.

Original languageEnglish
Pages (from-to)4839-4844
Number of pages6
JournalProceedings of the National Academy of Sciences of the United States of America
Issue number19
Publication statusPublished - 2018 May 8


  • Bilayer very low density amorphous ice
  • Confined water in nanoslit
  • Deeply supercooled water
  • Isochore end point
  • Two forms of liquid

ASJC Scopus subject areas

  • General


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