Here\u2019s what you\u2019ll learn when you read this story:<\/p>\n
Since 1948, scientists have wondered: If you could cool a glass over an extremely long period of time, would it eventually form an amorphous structure that behaves exactly like a crystalline lattice\u2014a state known as ideal glass?<\/p>\n<\/li>\n
Now, a new study has computationally constructed such a glass in two dimensions by forming a honeycomb-like structure (with the lattice removed) and allowing glass molecules to resize.<\/p>\n<\/li>\n
The resulting structure behaved perfectly like a crystal, but held an amorphous structure like glass\u2014possibly shining a light on how to more effectively form other materials.<\/p>\n<\/li>\n<\/ul>\n
Although we may take it for granted in our everyday lives (for the past 5,000 years or so<\/a>), glass is a bit of a scientific conundrum. While glass is most definitely a solid, it\u2019s made of disordered molecules like a liquid<\/a>. By some descriptions, that makes a glass a type of \u201cliquid in suspended animation<\/a>\u201d because its liquid-like molecules don\u2019t flow, and they also don\u2019t crystalize like a solid.<\/p>\n But in 1948, American chemist Walter Kauzmann proposed a strange question<\/a>: Could glass, if cooled slowly enough, form a perfect arrangement of the densest possible amount of molecules, or an ideal-glass state? Kauzmann realized that the slower you cool down a liquid, the more time the molecules would have to rearrange. So, once the liquid reached the same level of entropy<\/a> as typically exists when a crystal forms, the glass might form a perfect order where each molecule affects the position of the other. Unfortunately, cooling glass to this state would require essentially an infinite amount of time, and the overall paradoxical nature of \u201cideal glass\u201d eventually led Kauzmann to dismiss the idea.<\/p>\n However, in a new study published in the journal Physical Review Letters<\/a>, a team of researchers\u2014hailing from universities across the U.S. and led by Eric Corwin, a physicist from the University of Oregon (UO)\u2014computationally demonstrated that such an \u201cideal glass\u201d state is possible in two dimensions<\/a>.<\/p>\n \u201cIf you look at glass at a molecular level, you would see that the molecules are arranged amorphously. They\u2019re kind of random<\/a>. They\u2019re all pushed up against one another, but there\u2019s no structure,\u201d Corwin, senior author of the study, said in a press statement<\/a>. \u201cHow do you get stability, mechanical stability, in a system that is totally amorphous, that looks like a liquid?\u201d<\/p>\n To answer that question, Corwin and his team used UO\u2019s high-performance computer to computationally construct 2D disks clustered together (sort of like cells in a honeycomb) and then preserve that structure while removing the crystalline lattice. They then allowed the glass particles<\/a> to resize as they packed, and the resulting structure appeared amorphous like glass, but exhibited all known crystalline properties (such as how a material responds to pressure, bending, and melting).<\/p>\n \u201cWe think that we\u2019ve hit upon a resolution, by showing that such a state is not a paradox<\/a> at all; indeed we can construct it,\u201d Corwin told Phys.org<\/a>. \u201cWe\u2019ve shown that one can\u2019t hope to achieve these structures just by waiting, but that they nevertheless exist. The fact that a structure with no spatial ordering (i.e. an amorphous structure) can still be highly ordered in a more abstract sense (i.e. zero configurational entropy) is an enormous surprise.\u201d<\/p>\n While Corwin and his team still need to expand their research into three dimensions, understanding that \u201cideal glass\u201d can be constructed at all could improve manufacturing techniques for other materials<\/a>, including metallic glass (metallic structures with disordered configurations like glass).<\/p>\n