Method of manufacturing ductile glass discovered

If you have already dropped your smartphone on a concrete floor, you know that you feel dreaded when you flip it over to see how much the screen has cracked – but this stress could soon be a thing the past. Researchers at the Rensselaer Polytechnic Institute have discovered a way to make glass less fragile and less likely to break.

Their findings, led by Yunfeng Shi, Associate Professor of Materials Science and Engineering at Rensselaer, have recently been published in Nano Lett.

The glass currently used on many smartphones belongs to the family of oxide glasses, in which the silicon atoms generally bond to four oxygen atoms. This type of arrangement creates a rigid glass network that does not allow plastic deformation. Thus, when a significant external stress is applied, such as when a phone is dropped on hard ground, the glass breaks.

What Shi and his colleagues discovered during molecular simulations is that silica glass, obtained by compressing silica nanoparticles together, can be stretched up to 100% without breaking. They also discovered that improved ductility emerges when silicon binds to five oxygen atoms instead of four, Shi said. This is what is called silicon five times, and it is able to flow under stress.

"Compression really changes the structure of the material," said Shi.

This increased plasticity allows the glass to support more load without fracturing. Beyond our phones, the potential of this discovery extends to many applications.

"This glass is actually as rigid as steel, so if the glass can be hardened enough, it can replace steel," Shi said. "Our holy grail is to make a transparent structural material."

This discovery was made by means of molecular simulations. Now, says Shi, the next step is to test it in the lab.

Yanming Zhang, a graduate student in the Department of Materials Science and Engineering, is the first author of this paper. The work was done in collaboration with Liping Huang, professor of materials science and engineering.