The existence of plastic ice (plastic crystalline ice), predicted by the Tanaka group (the predecessor of our current laboratory) in 2008, has apparently been confirmed.

Ice VII, which forms under ultra-high pressure, is said to be extremely hard. However, when heated, before the crystal structure collapses entirely, it transforms into a very soft crystal (barely maintaining its structural integrity) where water molecules can rotate freely. This state is called plastic ice (plastic crystalline ice).

Our laboratory has theoretically predicted various physical properties of plastic ice from different angles over the years. With the confirmation of its actual existence, we expect verification of other properties to progress as well.

• Nature article Rescigno, M., Toffano, A., Ranieri, U., Andriambariarijaona, L., Gaal, R., Klotz, S., … Bove, L. E. (2025). Observation of plastic ice VII by quasi-elastic neutron scattering. Nature. DOI:10.1038/s41586-025-08750-4

• Introduction article on Karapaia

• Initial report: Takii, Y., Koga, K., & Tanaka, H. (2008). A plastic phase of water from computer simulation. The Journal of chemical physics, 128(20), 204501. https://doi.org/10.1063/1.2927255

• Follow-up studies:

  • Himoto, K., Matsumoto, M., & Tanaka, H. (2011). Lattice- and network-structure in plastic ice. Physical chemistry chemical physics: PCCP, 13(44), 19876–19881. DOI:10.1039/c1cp21871a
  • Himoto, K., Matsumoto, M., & Tanaka, H. (2014). Yet another criticality of water. Physical chemistry chemical physics: PCCP, 16(11), 5081–5087. DOI:10.1039/c3cp54726d
  • Matsumoto, M., Himoto, K., & Tanaka, H. (2014). Spin-One Ising Model for Ice VII–Plastic Ice Phase Transitions. The journal of physical chemistry. B, 118(47), 13387–13392. DOI:10.1021/jp5049502