Water Shifts Atomic Structure Under Extreme Pressure
Researchers discovered that water changes its atomic structure when subjected to extreme pressures, transforming into a lower-symmetry version of itself, according to a report from the University of Nevada, Las Vegas. The findings challenge long-held expectations about how materials behave under heavy compression.
Typically, when materials undergo compression, volume decreases and atoms are forced closer together. Observers expect this process to generate higher-symmetry arrangements of atoms. Water, however, demonstrates the exact opposite behavior.
As scientists squeeze water, its chemistry shifts. A new study from the University of Nevada, Las Vegas (UNLV), published in Communications Chemistry, details how applying intense force alters the liquid’s fundamental structural properties.
Recreating Ice Giant Conditions in the Laboratory
Ashkan Salamat, a UNLV physicist who directs the Nevada Extreme Conditions Lab and led the research, subjected water samples to the equivalent of 35 million pounds per square inch (PSI). For comparison, a standard car tire operates at approximately 30 PSI. This extreme pressure successfully replicated conditions found deep within the ice giants Neptune and Uranus.
These distant planets consist largely of molten, metallic-like water, ammonia, and methane. Direct exploration of their crusts and atmospheres remains impossible due to extreme distances, leaving researchers reliant on historical mission data.
“We can’t enter the crust or atmospheres of these planets because of distance, but we have data from things like the Voyager program,” Salamat noted regarding the planetary models.
By utilizing laboratory setups, researchers bridge the gap between historical space mission data and planetary interiors. “We have an idea of their compositions, and interior pressure and temperatures. And in labs like mine, we can mimic the chemistry and experiment with what could be occurring inside these planets,” Salamat explained.
Spectroscopy and Diamond Anvil Testing
To capture these atomic alterations, the research team placed water samples between two diamonds—the hardest known material—to generate extraordinary pressure levels. They then utilized X-rays to analyze the resulting structural arrangement of the atoms via spectroscopy.
The results show that water acts as a structural shapeshifter under cosmic pressures, taking on appearances entirely distinct from anything found naturally on Earth. If that extreme pressure were to dissipate, the water would revert to familiar terrestrial structures.
“Understanding the mechanisms of our solar system and our observable universe is critical for the endeavor of human knowledge,” Salamat stated. “When we eventually get to these worlds, what are we going to see? We’re really the initial pioneers in trying to answer these questions in the laboratory.”
