World’s largest X-ray laser discovers new type of ice, solid at room temperature

Scientists squeezed water between two diamonds to create an entirely new form of ice, solid at room temperature.

The ice, called XXI ice, forms when water is put under extreme pressure to become metastable – a precarious state that becomes physically unstable at the slightest disturbance.

The researchers created ice XXI by supercompressing water between two diamonds and detected it with the European X-ray Free Electron Laser (XFEL), the world’s largest X-ray laser. The team discovered that supercompressed water structurally changes from a high-density state to a very high-density state.

This discovery could have implications for space exploration, opening new pathways for ice formation on alien worlds, according to the study published October 10 in the journal Natural materials.

“Our results suggest that there may be a larger number of high-temperature metastable ice phases and their associated transition pathways, potentially offering new insights into the composition of icy moons,” co-author of the study. Rachel, husbandpostdoctoral researcher at the German Electronic Synchrotron Research Center in Germany, said in a statement statement.

Ice XXI, the number 21 in Roman numerals, is the 21st known phase of ice — others include the four-sided ice crystals XIX and hot like a star superionic ice. Water can exist in a multitude of solid-phase forms thanks to its molecular structure, with its two-pronged hydrogen atoms frozen into various crystalline and amorphous structures.

Scientists have discovered many water-ice transition pathways by applying pressure to water at low temperatures, when the molecules are slower, but they expect less ice diversity at higher temperatures, when the molecules have more kinetic energy.

In the new study, researchers explored glacial transition pathways at room temperature, or about 72 degrees Fahrenheit (22 degrees Celsius). The team used a diamond anvil cella device that takes advantage of the extreme hardness of diamonds to subject materials to immense pressure. In this case, the water was subjected to pressures about 20,000 times greater than normal air on Earth, forcing H2O molecules together until they were so compact that they formed a solid structure. The XFEL analyzed the sample every millionth of a second (1 microsecond), following the evolution of its structure.

“Using single X-ray pulses from the European XFEL, we discovered multiple crystallization pathways in H2O that were rapidly compressed and decompressed more than 1,000 times using a dynamic diamond anvil cell,” study co-author. Geun Woo Leea researcher from the Korea Research Institute for Standards and Science (KRISS) said in the statement.