Researchers at the Korea Research Institute of Standards and Science (KRISS) have made a groundbreaking discovery by identifying a new form of ice, officially named ice XXI. This novel ice forms under conditions typically associated with extreme pressure, but remarkably, it can exist at ambient temperatures. The study, conducted using advanced techniques, sheds light on the complex behavior of water and its ability to transform into various ice structures.
Ice is often perceived simply as frozen water, yet it can crystallize into over 20 distinct forms, each with unique atomic arrangements. While many of these forms require extreme conditions, the discovery of ice XXI suggests that water’s behavior is even more versatile than previously understood. The research was published in Nature Materials in March 2024.
Exploring Water’s Transformations
The investigation into this new ice type was spearheaded by Geun Woo Lee, a scientist at KRISS. By employing a combination of diamond anvil cells and X-ray lasers, the team observed how super-compressed water behaves at room temperature. Instead of freezing in a straightforward manner, the water underwent multiple freeze–melt cycles, leading to the formation of ice XXI within the pressure zone where ice VI typically occurs.
Ice XXI possesses a body-centered tetragonal crystal structure, distinguishing it from all previously known ice types. This ice is categorized as metastable, allowing it to persist in an unstable form under specific conditions. The implications of this discovery extend beyond mere academic curiosity; it offers insights into the physical properties of water in extreme environments, which may have applications in understanding icy planets and the Earth’s deep mantle.
Innovative Techniques and Findings
The experiments conducted by the KRISS team involved loading ultra-pure water into a minuscule metal chamber and applying high-pressure conditions. Researchers utilized high-speed cameras and laser-based sensors to closely monitor the water’s transformation. By adjusting pressure rhythmically, they captured detailed snapshots of how water froze and melted, observing changes in structure, pressure, and volume with exceptional accuracy.
Rachel Husband, another researcher in the team, emphasized the significance of their findings, stating, “The results suggest that a greater number of high-temperature metastable ice phases and their associated transition pathways may exist, potentially offering new insights into the composition of icy moons.”
In their high-pressure experiments, the scientists discovered that water does not freeze via a single, linear pathway. Instead, it follows at least five different routes, showcasing the complexity of its behavior under varying conditions.
The powerful X-ray beams used during the research facilitated the identification of the transformation from liquid water to ice. The scattered X-ray signals were meticulously analyzed using a program called DIOPTAS, which helped in understanding the intricate processes occurring during the phase transitions.
This discovery opens up exciting avenues for further research into the properties of water and its various forms. As scientists continue to probe the mysteries of ice, ice XXI stands out as a testament to the dynamic nature of water and the many forms it can take, even under seemingly ordinary conditions.
