Scientists have created a new phase of ice that can form at room temperature.
As detailed in a new article published in the journal Natural materialsthe new phase, called XXI, requires extreme pressure levels to form. As its name suggests, it is the twenty-first ice shape identified, joining a fascinating array of other structures ranging from hexagonal to cubic to superionic, which can be found on the surfaces of gas and ice giants like Neptune or Uranus.
This discovery shows just how many phases there actually are in the solid state of water – and how much there is still to learn about these extremely abundant substances. The research could even help explain how alien ice forms found on distant moons came to be.
The research is a collaboration between Geun Woo Lee, a researcher at the Korea Research Institute of Standards and Science (KRISS), and scientists from the European X-ray Free Electron Laser Facility (XFEL), the world’s largest X-ray laser, and the German Electron Synchrotron Research Center (DESY).
XXI ice forms when water is rapidly compressed to extraordinary levels at room temperature. It is only stable under extremely specific conditions.
This is a major exception in the group of nearly two dozen ice forms we know of, because most of them form at high or low temperatures, according to a research report.
“The rapid compression of water allows it to remain liquid until higher pressures, where it should have already crystallized into ice VI,” Lee explained, referring to a phase thought to be inside the icy moons Titan and Ganymede.
In other words, XXI appears to be a possible intermediate stage between water and the exotic ice phase found on distant icy moons.
Using a diamond anvil cell, a high-pressure device used in materials science to recreate the pressures found deep within planets, the team observed what happened when water was subjected to a pressure of two gigapascals, or about 20,000 times atmospheric pressure.
They then released the pressure for a second to see how the crystal structures would react, before repeating the process hundreds of times.
Although at room temperature, the water molecules bunched together to form ice, albeit in a much tighter structure.
The team then used the XFEL to capture images of the sample every microsecond, the equivalent of capturing images with a high-speed camera, to observe the formation of the ice structure.
“Using the unique X-ray pulses from the European XFEL, we discovered multiple crystallization pathways in H2O that was rapidly compressed and decompressed more than 1,000 times using a dynamic diamond anvil cell,” Lee explained.
“Our results suggest that a larger number of high-temperature metastable ice phases and their associated transition pathways may exist, potentially providing new insights into the composition of icy moons,” added co-author and DESY researcher Rachel Husband.
Learn more about popsicle: NASA’s James Webb Telescope Just Found Frozen Water Around Another Star
