Making glass flex, not fracture


It must be dense and flawless, study suggests.


Producing ductile glass. Highly energetic laser pulses are shot to the crystalline target on the left side of the image. The intense energy breaks down the crystalline aluminium oxide into purple coloured plasma, which injects outwards at high speed. The plasma cools extremely quickly to form a film of glassy (amorphous) aluminium oxide upon colliding with the substrate on the right side of the image.

Erkka Frankberg

Glass is strong, despite being brittle. Imagine its potential if it wasn’t.

That’s not totally out of the question, according to a team of mainly European researchers.

Writing in the journal Science, they describe how thin films of amorphous aluminium oxide (a-Al2O3) glass can be permanently bent and pulled under high stress without breaking at room temperatures.

Led by Erkka Frankberg, from Tampere University in Finland, the researchers used direct microscopy and simulated observations to reveal that the high plasticity of a-Al2O3 requires the material to be dense and flawless, illuminating key criteria that could identify other oxide glasses with similar malleability.

The results suggest, they say, that oxide glasses are not inherently brittle; rather our ability to manufacture such a flawless glass in bulk and at larger scales is lacking.

It was a small study, and as Lothar Wondraczek, from the University of Jena, Germany, writes in a related Perspective in the same journal, “it will not be easy to put to use these findings in the design of commodity glass products just now”.

Nonetheless, it suggests that what Wondraczek calls something of a “holy grail” for engineers – improving the strength and ductility of oxide glasses – is not out of reach.

Explore #glass
  1. https://science.sciencemag.org/content/366/6467/864
  2. https://science.sciencemag.org/content/366/6467/804
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