New Definition Of Glass Describes Non-Equilibrium State Of Matter Ending In Crystallization

Glass is a material that seems to have a split personality. Is it a solid? Is it a liquid? Could it be both? A simple Google search brings up dozens of articles on the topic. And if you peruse the results, you encounter a variety of opinions on the subject. Unlike liquids, atoms in most solid materials are arranged in an orderly crystalline structure. Atoms in liquids can’t seem to sit still—they’re constantly moving, like young children after a large dose of sugar. Glass’s atoms are not arranged like other neat and tidy solids. That’s why glass is a non-crystalline material—one that is not organized in a distinct pattern or shape. The glass transition from liquid to solid happens so fast that the atoms and molecules don’t have time to get their act together and line up in an orderly fashion. What happens to glass over a long period of time? Researchers have already debunked the flowing glass window myth earlier this year by proving that the glass in medieval windows doesn’t succumb to gravity. So who better to weigh in on the glass solid–liquid debate than people who study glass for a living? Researchers Edgar Zanotto, professor in the Department of Materials Engineering at the Federal University of São Carlos, and John Mauro, professor of materials science and engineering at Penn State University, have authored a new definition of glass, recently published in the Journal of Non-Crystalline Solids. “There are several definitions of glass, but most of them contain serious errors,” Zanotto explains in a news release on Agência FAPESP. “Many definitions say glass is a solid, and others say it’s an isotropic material [whose properties are the same in all directions], but many glasses are not.” “Glass is neither a true solid nor a true liquid, but rather a unique hybrid phase that combines both solid-like and liquid-like qualities,” Mauro states. To read this article in full, please visit the above-mentioned website.