Most people are familiar with the three states of matter of water: ice, liquid water, and water vapor. However, recently a team led by Alexander Rosu-Finsen at University College London (UCL) has created a new type of ice: medium-density amorphous ice. Amorphous ice has no structure; all the molecules are joined haphazardly together, whereas, with regular ice, the structure of the molecules is hexagonal. This is a big find as this type of ice follows the density and structure of liquid water.
In the last century, two previous types of amorphous ice were discovered: low-density amorphous ice and high-density amorphous ice. Low-density amorphous ice was discovered as water vapor froze on a very cold surface that was under -150 degrees Celsius. High-density amorphous ice is created by compressing regular ice under pressure at -150 degrees Celsius. Neither type of ice is common on Earth, but there is an abundance of them in space. The difference between these types of amorphous ice and the newly discovered one is that the densities of the low-density and high-density types are lower and higher, respectively, compared to the medium-density ice. The newly created medium-density ice replicates the structure of liquid water the most.
The process with which this new form of ice was created was relatively simple. Scientists utilized a tool known as the ball mill which is normally used to grind materials while processing minerals. Here, the way the scientists used this technology was by putting regular ice and steel balls that were cooled at 77 degrees Kelvins inside of a container and shaking the container 20 times per second. The force on the ice would cause it to break down into a white powder. Afterward, to study the molecular structure, the team fired X-rays at the powder and recorded how it bounced off. Christoph Salzmann, a chemist at UCL and a co-author of this study, explained how the powder’s density was similar to that of water and there was no coherent structure to this new form of ice. Salzmann stated, “You’re looking at a very disordered material,” in response to the destroyed crystallized form.
While this process led scientists to discover a new form of amorphous ice, many questions still remain unanswered. Scientists are still unsure if the amorphous ice can be reproduced using the liquid form of water directly since regular ice was used in the experiment. This also makes it difficult for them to determine the medium-density ice’s relationship to water as not all amorphous ice has a connection with its liquid state.
The implications of this study are many. The discovery of this version of ice can help better understand water as it is more complex to study than other liquids. Additionally, Salzmann discussed the use of these findings in the study of the geophysics of the icy moons of some of the planets in our solar system. He theorizes that if the ice on the icy moons of Saturn or Jupiter start to rub together, they could end up producing the medium-density amorphous ice that was developed in the lab. Salzmann claimed, “There would be a massive collapse of the ice. It could have severe implications for the geophysics of the icy moons.”
In short, the discovery of medium-density amorphous ice could open up a new field of study for researchers to look into. Since the creation of this form of ice has yet to be connected with liquid water it is presumably evident that scientists will first try to see if it has ties to liquid water. Regardless of the findings, the discovery and the additional studies done on medium-density amorphous ice will surely help researchers get closer to explaining the properties of water.
