The blackjack of ice

Subjects Phase transitions and critical phenomenaStructure of solids and liquids Five different crystallization pathways of high-density ice at room temperature reveal a metastable ice phase with a body-centred tetragonal structure, termed ice XXI. Access through your institution Buy or subscribe This is a preview of subscription content, access via your institution Access options Access through your institution Access Nature and 54 other Nature Portfolio journals Get Nature+, our best-value online-access subscription $32.99 / 30 days cancel any time Learn more Subscribe to this journal Receive 12 print issues and online access $259.00 per year only $21.58 per issue Learn more Rent or buy this article Prices vary by article type from$1.95 to$39.95 Learn more Prices may be subject to local taxes which are calculated during checkout Fig. 1: P–t curves during compression and decompression cycles for a microscopic water sample at room temperature. ReferencesLoerting, T., Fuentes-Landete, V., Tonauer, C. M. & Gasser, T. M. Commun. Chem. 3, 109 (2020).Article CAS PubMed PubMed Central Google Scholar Hansen, T. C. Nat. Commun. 12, 3161 (2021).Article CAS PubMed PubMed Central Google Scholar Prakapenka, V. B., Holtgrewe, N., Lobanov, S. S. & Goncharov, A. F. Nat. Phys. 17, 1233–1238 (2021).Article CAS Google Scholar Ostwald, W. Z. Phys. Chem. 22U, 289–330 (1897).Article Google Scholar Lee, Y.-H. et al. Nat. Mater. https://doi.org/10.1038/s41563-025-02364-x (2025).Article PubMed PubMed Central Google Scholar Pépin, C. M. et al. Nat. Commun. 15, 8239 (2024).Article PubMed PubMed Central Google Scholar Howard, A., Kim, M., Smith, J. & Yoo, C.-S. Phys. Rev. B 111, 104105 (2025).Article CAS Google Scholar Husband, R. J. et al. J. Synchrotron Radiat. 30, 671–685 (2023).Article CAS PubMed PubMed Central Google Scholar Kobayashi, H. et al. Preprint at https://doi.org/10.48550/arXiv.2507.14415 (2025).Piaggi, P. M., Weis, J., Panagiotopoulos, A. Z., Debenedetti, P. G. & Car, R. Proc. Natl. Acad. Sci. USA 119, e2207294119 (2022).Article CAS PubMed PubMed Central Google Scholar Download referencesAuthor informationAuthors and AffiliationsDepartment of Applied Physics, KTH Royal Institute of Technology, Stockholm, SwedenJonas A. SellbergAuthorsJonas A. SellbergView author publicationsSearch author on:PubMed Google ScholarCorresponding authorCorrespondence to Jonas A. Sellberg.Ethics declarations Competing interests The author declares no competing interests. Rights and permissionsReprints and permissionsAbout this articleCite this articleSellberg, J.A. The blackjack of ice. Nat. Mater. (2025). https://doi.org/10.1038/s41563-025-02439-9Download citationPublished: 18 December 2025Version of record: 18 December 2025DOI: https://doi.org/10.1038/s41563-025-02439-9Share this articleAnyone you share the following link with will be able to read this content:Get shareable linkSorry, a shareable link is not currently available for this article.Copy shareable link to clipboard Provided by the Springer Nature SharedIt content-sharing initiative Multiple freezing–melting pathways of high-density ice through ice XXI phase at room temperature Yun-Hee LeeJin Kyun KimGeun Woo Lee Nature Materials Article Open Access 10 Oct 2025