Researchers develop process to make ductile glass

 

Researchers at Rensselaer Polytechnic Institute (Troy, N.Y., U.S.) are developing a method for making glass that is less brittle and less likely to break for applications such as smartphone screens. The researchers’ findings, led by Yunfeng Shi, an associate professor of materials science and engineering at Rensselaer, were recently published in the journal Nano Letters.

According to Rensselaer, the glass currently used on many smartphones belongs to the oxide glass family, in which silicon atoms generally bond to four oxygen atoms. That type of bonding arrangement creates a rigid glass network that doesn’t allow plastic deformation, and if significant external stress is applied — as it is when a phone is dropped on a hard floor, for example — the glass breaks.

Through molecular simulations, Shi and his colleagues found that silica glass, made by compressing silica nanoparticles together, can be stretched up to 100% without breaking. They also discovered that enhanced ductility emerges when silicon bonds with five oxygen atoms instead of four, Shi said. This is known as five-fold silicon, and it’s capable of shear flow under stress: “The compression actually changes the material structure,” Shi says.

This enhanced plasticity enables the glass to withstand more load without fracturing. Beyond smartphones, the researchers say the potential of this finding extends to structural applications, as well.

“This glass is actually as stiff as steel. So, if the glass can be toughened sufficiently, it can replace steel,” Shi says. “Our holy grail is to make a transparent structural material.”

This discovery was made through molecular simulations. The next step, Shi says, is to test it in the lab.

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