X-ray photons fluidize the atoms of oxide glasses

What is it about?

Normally, atoms in glasses cannot freely move within the bulk and they need a lot of time (geological eras) to rearrange their configuration at microscopic length-scales. We observe that exposing oxide glasses to X- rays it is possible to induce movements of the atoms similar to charged particles accelerating in interstellar space and somewhat different from atoms diffusing in a molten glass. These movements involve all the particles in the glass and lead to a complete renewal of the atomic configuration in the illuminated volume.

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Photo by Vince Fleming on Unsplash

Photo by Vince Fleming on Unsplash

Why is it important?

Glasses, and in particular silicates like SiO 2 , represent a big portion of the materials used to manufacture everyday objects. For example, SiO 2 is the main component of items such as windows, screens or bottles. Typically, the properties of glasses are controlled with specific thermal treatments but this X-ray fluidization takes place at room temperature. The origin of this process is still debated, but our experiment can track movements of the atoms from interatomic distances up to several nanometers. The observed dynamics follow the rules of what is known as “hyper-transport”, meaning that the distance covered by the atoms increases with time at a higher rate not only with respect to simple diffusion but also to particles moving at constant speed.