Ice I c without stacking disorder by evacuating hydrogen from hydrogen hydrate

• Published in: Nature communications 2020-02, Vol.11 (1), p.464
• Main Authors: Komatsu, Kazuki, Machida, Shinichi, Noritake, Fumiya, Hattori, Takanori, Sano-Furukawa, Asami, Yamane, Ryo, Yamashita, Keishiro, Kagi, Hiroyuki
• Format: Article
• Language: English
• ISSN: 2041-1723
• DOI: 10.1038/s41467-020-14346-5

Water freezes below 0 °C at ambient pressure ordinarily to ice I , with hexagonal stacking sequence. Under certain conditions, ice with a cubic stacking sequence can also be formed, but ideal ice I without stacking-disorder has never been formed until recently. Here we demonstrate a route to obtain ice I without stacking-disorder by degassing hydrogen from the high-pressure form of hydrogen hydrate, C , which has a host framework isostructural with ice I . The stacking-disorder free ice I is formed from C via an intermediate amorphous or nano-crystalline form under decompression, unlike the direct transformations occurring in ice XVI from neon hydrate, or ice XVII from hydrogen hydrate. The obtained ice I shows remarkable thermal stability, until the phase transition to ice I at 250 K, originating from the lack of dislocations. This discovery of ideal ice I will promote understanding of the role of stacking-disorder on the physical properties of ice as a counter end-member of ice I .