In an article published in the journal Nature Scientific Reports, researchers from the University of Tokyo and Japan’s Synchrotron Radiation Research Institute describe a new material significantly sturdier, lighter, and thinner than traditional, silica-based glass. Part of the secret’s aluminum: scientists crushed alumina oxide powder, a form of aluminum commonly found in plastics, sunscreen, paint, and cosmetics, and combined tantalum oxide powder. In a process known as “aerodynamic levitation technique,” the team applied heat to the samples, injected them with oxygen gas to send them airborne, and shot “levitating” samples with carbon dioxide lasers. The result? Tiny, nanonmeter-long spheres of super-hard glass.
Alumina-based glass, Forbes points out, is nothing new; a 2000 study published in the Journal of the Japan Institute of Metals and Materials involved processing a form of aluminum oxide glass. But past forays into all-alumina glass manufacturing haven’t been successful for two reasons: 1) alumina has a melting point several hundred degrees higher than silica (2,072 degrees Celsius versus 1,713 degrees), and 2) an annoying habit of forming jagged crystals when formed in a container. The latter’s a process known as nucleation: liquids crystallize around any present solid particles (think water freezing to ice on the side of a solid object).
The keys to the University of Tokyo team’s success were its use of both a stabilizing element and “levitation.” By combining tantalum oxide with a 50 percent mixture of alumina, the researchers successfully combated the alumina’s undesirable tendencies. And by forming the glass in midair rather than a container, they minimized any crystal formation; without a point of nucleation, the liquid alumina turned to imperfection-free glass.
Just how tough is the new glass mixture, though? Theoretically, very — the alumina oxide used in the study, the mineral corundum, is second only to diamonds on the Moh’s scale of hardness. (Some reports on the study have compared its rigidity to steel and iron.) But it’s not quite a miracle glass: the researchers applied forces to the glass spheres and found that while they performed on par with industrial glass, they weren’t exactly indestructible. After a certain pressure, the samples developed the “radial,” spider web-like cracks all too familiar to owners of a smashed smartphone.
Still, the scientists envision a number of possible applications for the glass. Imagine thin, light windows with the toughness of reinforced traditional glass, or a glass pitcher that lands (somewhat) gracefully when dropped rather than chipping or shattering. It’s a future that might not be far away. “We will establish a way to mass-produce the new material shortly, University of Tokyo assistant professor Atsunobu Masuna, a coauthor of the paper, told Japanese publication The Asahi Shambun. “We are looking to commercialize the technique within five years.”
Perhaps more exiting, though, is what’s around the corner. The scientists are confident they’ll be able to produce even stronger glass — glass with “good mechanical properties, high transparency and a high refractive,” as the material in the study — in the next few years.
The takeaway, then? The shatter-proof smartphone screen may not be here yet, but it won’t be long now. Take comfort in that thought, butterfingered users of the world.
