Scientists Use Extreme Heat and Pressure to Create Strongest Glass Ever

The modern smartphone came about thanks to numerous technologies, including more powerful mobile processors and enhanced mobile networks, but we cannot discount the effect of hardened glass. Materials like Corning Gorilla Glass made it possible to carry a glass sandwich in your pocket without getting shards of glass stuck in your leg every time you bump into a table, but even the latest durable glass materials are a weak point. That might not be true if an experimental material from the University of Bayreuth in Germany lives up to the hype. Researchers say they’ve created an aluminosilicate glass that is much harder to break.

According to the study, which was published in Nature Materials, the researchers started with common oxide glass. This was combined with aluminosilicate, which contains silicon, aluminum, boron, and oxygen. Using high pressure and temperature, the team was able to give the glass a new structure based on paracrystallization.

The glass was heated to 1,832 degrees Fahrenheit (1,000 degrees Celsius) under a pressure of between 10 and 15 gigapascals. Under these conditions, the aluminosilicate morphs into a crystal-like structure—it’s called paracrystalline because it’s more ordered than typical glass but not as regular as a true crystal structure. It’s like an intermediate stage between amorphous and crystalline materials. You can see the high-pressure press above with lead author Hu Tang.

When the glass is freed from extreme heat and pressure, the paracrystalline structures remain intact. The researchers measured the fracture strength at 1.99 megapascals, a significant improvement over the chemically strengthened glass currently on the market. For example, Corning claims Gorilla Glass Victus has a fracture toughness rating of 0.76 megapascals.

Left: amorphous glass, Right: Paracrystalline glass; the lighter regions are more ordered.
Credit: University of Bayreuth / Hu Tang

In other glasses, external forces lead to microscopic breaks and internal cracks. Eventually, such stress can result in fractures, even if the most recent impact was relatively weak. In the experimental aluminosilicate glass, these forces are absorbed by the paracrystalline structures. The structures dissolve to return the glass to its amorphous, disordered state. It doesn’t crack, though.

Currently, this material only exists as small samples in the lab at the university’s Bavarian Research Institute of Experimental Geochemistry and Geophysics. It’s unclear if the manufacturing process can be scaled up to the level required for commercial glass products, but the team is going to try. “Our discovery highlights an effective strategy for developing highly damage-tolerant glass materials, which we plan to pursue with our research in the coming years,” says Tang.