Two researchers working at Universita di Roma, Frank Smallenburg and Francesco Sciortino have shown via computer simulation that certain colloids can be made to form into a stable non-crystalline state at below freezing temperatures. In their paper published in the journal Nature Physics, the two describe how they used a computer simulation to manipulate virtual flexible bonds representing real colloids and discovered they could be made to hold their liquid-like structure even at very low temperatures.
In the natural world, when liquids are frozen they form into crystals. This is because as heat dissipates a crystalline structure is favored because it’s the most energy efficient state. One exception to the rule is glass, which exists as both a liquid and a solid. Now it appears there are other exceptions as well.
In their work studying colloids (liquids with tiny particles suspended in them—milk, wine, etc.) the researchers noted the flexible bonds that existed between the particles—pure liquids such as water typically have few bonds between the molecules in them and as a result are relatively stiff. Colloids also have more of the bonds that tie them together offering more possibilities for joining configurations as heat energy is reduced pulling the molecules closer together. In manipulating the way the bonds formed between the various molecules in their simulation, the two researchers found that they could prevent the liquid from forming as a crystal when the temperature was lowered. The result was a frozen material that was not crystallized, which technically—because its molecules were unordered—makes it a liquid. Remarkably, the frozen colloids were more stable than they would have been had they been allowed to form into crystals. The researchers note it appears the colloids would not crystallize as the temperature was dropped even lower, unless they were highly compressed.
Read more at: Phys.org