Scientists at the University of Edinburgh in Scotland has created a new state of matter: a state that can be described as liquid and solid at the same time. Through a study published on April 9, the scientists have proved the long researched theory that matter can be in a solid and liquid state at the same time.
Indeed, matter is normally found only in 3 forms, liquid, solid or gaseous. But under extreme pressure and temperature conditions, its atoms can make it both solid and liquid.
To confirm this theory, scientists used artificial intelligence and simulated the behavior of a set of potassium atoms subjected to these extreme conditions.
Between 126 and 526 degrees, potassium becomes liquid and solid at the same time
With this experiment, the scientists were able to confirm that between 20,000 and 40,000 times the atmospheric pressure and between 126 and 526 degrees, the atom set enters a state that can be described as a “chain-melted state ” where it dissolves in liquid and remains solid at the same time.
Dr. Andreas Hermann, who conducted the study, explained that they managed to show “that this unusual and yet stable state is both solid and liquid. Recreating this state for other matter could help to think of all sorts of things.”
This unusual state of potassium could exist in the conditions found in the mantle of the Earth, but the element is not generally found in pure form and is usually related to another material. Similar simulations could help study the behavior of other minerals in such extreme environments.
A chain-melted state
Metals like potassium are quite simple at the microscopic level. When they are formed into a solid bar, the atoms of the element come together in ordered rows that conduct heat and electricity well. For a long time, researchers believed that they could easily predict what might happen in such crystalline structures under pressure.
But about 15 years ago, scientists discovered that sodium, a metal with properties similar to potassium, did something strange when compressed. At 20,000 times the pressure present on the surface of the Earth, sodium was transformed from a silvery block into a transparent material, one that did not conduct electricity but impeded its flow. By exploring the sodium with X-rays, the scientists could see that their atoms had taken a complex crystal formation instead of a simple one.
Potassium, too, has been subjected to much experimental scrutiny. When compressed to similar extremes, their atoms are organized into an elaborate formation: five cylindrical tubes organized in an X-shape, with four long chains seated in the folds of this set, almost like two separate and non-interlaced materials.
“Somehow, these potassium atoms decide to split into two linked sub-lattices,” says Hermann. But as the scientists increased the heat, the X-ray images showed the disappearance of the four chains, and the researchers discussed exactly what was happening.
Hermann and his colleagues resorted to simulations to discover, using what is known as a neural network, an artificial intelligence machine that learns to predict behavior based on previous examples. After being trained in small groups of potassium atoms, the neural network learned quantum mechanics well enough to simulate collections containing tens of thousands of atoms.
Computer models confirmed that between approximately 20,000 and 40,000 times the atmospheric pressure and from 127 to 527 degrees Celsius (260 to 980 degrees Fahrenheit), potassium entered what is called a molten-chain state, in which the chains are dissolved in liquid while the remaining potassium crystals remained solid.
This is the first time that scientists have shown that this state is thermodynamically stable for any element.
The machine learning technique developed by the team could be useful in modeling the behavior of other substances, says Marius Millot, who studies the material in extreme conditions at the Lawrence Livermore National Laboratory. “Most of the matter in the universe is at high pressures and temperatures, for example, inside planets and stars,” he adds.