As children, we were taught that matter exists in three phases: solid, liquid and gas. It wasn’t until the discovery of graphene, some twelve years ago, that the scientific world finally acknowledged a new phase, that of two-dimensional materials. Although it is commonly believed that 2D solids do indeed exist, the same cannot be said about one-atom-thick liquids. This is primarily because such fragile membranes are generally thought to be incapable of withstanding the thermal atomic motion of liquid molecules. However, a recent research, conducted at Finland’s University of Jyväskylä, has predicted an entirely new phase of matter: flat two-dimensional liquid.
Led by scientist Pekka Koskinen, the researchers have managed to achieve such a feat with the help of specially-developed computer simulations, using particular quantum-mechanical models. The new phase could theoretically be observed when liquid gold is stretched across the minute pores of graphene. According to the team, while the gold atoms constantly flow and change places, the atomically-thin graphene frame maintains the planarity of the liquid material. Speaking about the project, Koskinen explained:
Here the role of graphene is similar to circular rings through which children blow soap bubbles. The liquid state is possible when the edge of graphene pore stretches the metallic membrane and keeps it steady.
It should be noted that the breakthrough currently exists only in the form of a computer model, and will have to be confirmed through experiments and practical testing. The simulations suggest that, for a two-dimensional liquid to actually exist, the material needs to spread out, into a one-atom-thick layer, before the atomic fluctuations manage to rupture the thin membrane. Furthermore, the bond, between the liquid material and the solid temperate, should remain stable, even at very high temperatures. The study’s lead author said:
Unfortunately, simulations suggest that the flat liquid is volatile. In experiments the liquid membrane might burst too early, like a soap bubble that bursts before one gets a proper look at it. But again, even graphene was previously considered too unstable to exist.
The research, recently published in the Nanoscale journal, was funded with the grant from the Academy of Finland.