Abandoning old assumptions and applying new techniques, scientists have discovered three new kinds of ice in the past year, including two of the most complex ice phases ever seen. \u201cIt seems a remarkable time at the moment,\u201d said Chris Pickard<\/a>, a physicist at the University of Cambridge. \u201cThey\u2019re really finding a lot more of these structures.\u201d<\/p>\n Space Oddity<\/p>\n The shape of water makes it exceptionally versatile. Its molecular structure can assemble in many possible configurations.<\/p>\n Each water molecule looks like a central unit with four arms spread apart by the electromagnetic force. The central unit is an oxygen atom. Bonded to it are two hydrogen atoms, and sticking out like extra limbs are two pairs of leftover free electrons.<\/p>\n Mark Belan\/Quanta Magazine<\/p>\n In the most common form of ice, these building blocks combine to form a cagelike hexagonal structure. The spaciousness of this arrangement makes typical ice less dense than liquid water. This is why ice floats, and why bodies of water freeze from the top down, allowing underwater life to survive the winter.<\/p>\n Put water under pressure, though, and its shape can compress and overlap in a seemingly endless bounty of possible patterns. Because it can take so many different forms, \u201cthe physics and the chemistry of water can be completely different\u201d from one environment to the next, said Livia Bove<\/a>, a physicist at the Swiss Federal Institute of Technology Lausanne. \u201cIt\u2019s topologically beautiful.\u201d<\/p>\n In 2018, an international research group from Europe and Japan created an ambitious computer simulation<\/a> of the dynamics of water molecules that aimed to predict undiscovered forms of ice. The result was a catalog of over 75,000 phases, each characterized by a slightly different way that the water molecules could fit together when subjected to a different combination of temperature and pressure.<\/p>\n Livia Bove\u2019s team recently discovered a type of \u201cplastic\u201d ice that\u2019s thought to exist in the cores of icy moons.<\/p>\n Courtesy of Livia E. Bove<\/p>\n In reality, scientists don\u2019t expect to find anywhere near that many phases; just because a structure is mathematically possible does not mean that it will form in nature. \u201cThere is always a bit of uncertainty associated with claims of the existence of new phases when they are solely based on simulations,\u201d wrote Federica Coppari<\/a>, a physicist at LLNL, in an email.<\/p>\n Some phases would require a ridiculous amount of energy to form. Others are so fragile that they would collapse immediately. Scientists try to narrow their predictions down to just those that seem viable. \u201cIt filters down to fewer of them,\u201d said Pickard, who worked on the simulation. \u201cBut the reality is, we don\u2019t exactly know how to place that filter.\u201d<\/p>\n To discover the forms that ice actually takes, scientists head to the laboratory.<\/p>\n Under Pressure<\/p>\n In 2018, Yong-Jae Kim was a postdoc at the Korea Research Institute of Standards and Science (KRISS) studying how room-temperature water turns to ice under extreme pressure. The experiment involved squeezing a drop of water between two diamonds and studying its changing molecular structure with high-speed imaging and other analysis techniques.<\/p>\n Going through the data from the experiment, Kim noticed what at first looked like a mistake. For just a few tens of milliseconds, the ice seemed to lose its structure, dissolving into a mess of molecules before transitioning to its next phase. Kim worried that sweat or dirt had contaminated the water. \u201cAt that stage, I felt more anxious than excited,\u201d he said. He shared the observation with the rest of his team, but he ran out of time to follow up on it.<\/p>\n In 2025, researchers at KRISS ran an improved version of the same experiment using Kim\u2019s diamond system and managed to re-create the strange structure. It was so complex that at first it looked almost random. \u201cBut step out,\u201d Kim said, \u201cand we see the structure macroscopically. It has a periodicity.\u201d<\/p>\n You take water, and just the way you compress it \u2014 a little bit faster, a bit slower, up and down, at the right timescale \u2014 and then you can find this completely unexpected behavior.<\/p>\n Marius Millot, Lawrence Livermore National Laboratory<\/p>\n The researchers took their setup to the European X-Ray Free-Electron Laser Facility in Germany, which houses a laser that accelerates electrons through a 3.4-kilometer-long tunnel and then sends them through special magnets to produce bursts of X-rays. \u201cThe brighter the beams of X-rays, the better pictures you get of your crystal structures,\u201d Pickard said.<\/p>\n The scientists shone high-powered X-ray laser beams through the ice and measured how the beams scattered. Most phases of ice send the rays bouncing in just a couple different directions, since their crystal patterns repeat after a few molecules. But this sample sent the light along roughly 15 different paths. When the scientists analyzed the images, the number of molecules in the crystal pattern came to a whopping 152. The team\u2019s observation of the structure earned the phase of ice an official Roman numeral name, ice XXI.<\/p>\n What\u2019s more, the new phase was a total surprise. The team scoured the tens of thousands of phases predicted by Pickard\u2019s group in search of a match, but they didn\u2019t find one. The repeating structure of ice XXI, it turned out, was beyond the size at which the simulation capped its search. \u201cThey basically found something much more complicated than we did,\u201d Pickard said.<\/p>\n Unbeknownst to the KRISS team, a group from Okayama University had actually predicted the structure in a different, narrower simulation<\/a> also created in 2018. The more focused simulation predicted two additional phases of ice that are still undiscovered.<\/p>\n Changes<\/p>\n The researchers at KRISS and Kim, now at LLNL, had not set out to discover a new phase of ice. Rather, they wanted to investigate another of water\u2019s strange properties, related to how it transitions from phase to phase. The classical theory of phase transitions predicts that any system will return to its lowest-energy state. But water does not always follow predictions.<\/p>\n Chris Pickard worked on a simulation that created a catalog of more than 75,000 possible forms of ice.<\/p>\n Courtesy of Chris Pickard<\/p>\n For example, Kim\u2019s sample did not respond to being squeezed by the diamond device by jumping straight to its most stable state,\u00a0which at that level of pressure would be a form called ice VI. Instead, it hopped from water to ice XXI, and then to ice VII. These in-between phases are called metastable states, and their existence demonstrates that some phase transitions happen in steps, rather than all at once.<\/p>\n Water\u2019s metastable states support a theory of phase transitions called Ostwald\u2019s step rule, named for Wilhelm Ostwald, a German physical chemist and a peer of Albert Einstein. (Einstein was initially rejected for a job in Ostwald\u2019s laboratory, but the two later became friends, and Ostwald eventually nominated Einstein for the Nobel Prize.) Ostwald\u2019s step rule suggests that systems transition to the closest and easiest-to-reach phase state rather than the most thermodynamically stable one \u2014 and that they sometimes then get stuck. \u201cIt\u2019s a nicely paradoxical thing that sometimes the easiest [state] to form is the one that\u2019s the least stable,\u201d Pickard said.<\/p>\n![\"\"](\"https:\/\/www.quantamagazine.org\/wp-content\/uploads\/2026\/04\/The_Shapes_of_Water-crMarkBelan-Desktop-v5.svg\")
![\"\"](\"https:\/\/www.quantamagazine.org\/wp-content\/uploads\/2026\/04\/The_Shapes_of_Water-crMarkBelan-Mobile-v5.svg\")
<\/p>\n![\"A](\"https:\/\/www.newsbeep.com\/au\/wp-content\/uploads\/2026\/04\/Livia-Bove-co.-Livia-Bove-1.webp.webp\")
<\/p>\n![\"Portrait](\"https:\/\/www.newsbeep.com\/au\/wp-content\/uploads\/2026\/04\/Chris-Pickard-with-Background.webp.webp\")
<\/p>\n