Synopsis: Hard to resist

A simple relation ties the hardness of inorganic glasses to the number of ways its structure is constrained from yielding to pressure.

Generally speaking, hardness is the ability of one material to resist being permanently deformed by another, but actually quantifying the atomic structures that make one material hard—particularly if it has an amorphous structure like glass—has proven to be a major challenge in materials science.

In a paper appearing in Physical Review Letters, Morten Smedskjaer and Yuanzheng Yue at Aalborg University, Denmark, and John Mauro at Corning Incorporated, US, show they can predict the hardness of different types of inorganic glasses from a simple analysis of its structure and topology.

In their study, Smedskjaer et al. pursue the idea that a glass will be harder the more constraints there are, such as rigid bonds and complex configurations, which prevent it from giving way to pressure. In this picture, a string of atoms that is rigid in only one direction has fewer constraints than a sheet with strong bonds in two dimensions. Focusing on a series of soda lime borate glasses with different sodium content, they calculate the number of constraints associated with each composition and feed this number into an equation that yields the hardness of the glass, in units of pressure. The soda lime borate glasses under study are similar to, but structurally more complicated than, soda lime silicate glass used for windows, bottles, and other common glass products.

The predicted results from their model compare well with hardness measurements on actual glasses, suggesting that knowing the network topology of glasses is enough to determine their hardness. This sort of predictive power has an important application in research and manufacturing, where ideally, the effects of changing the composition of a glass could be deduced before actually being produced. – Jessica Thomas


Announcements

More Announcements »

Subject Areas

Materials Science

Previous Synopsis

Mesoscopics

Where stripes come from

Read More »

Next Synopsis

Nanophysics

Master of no domain

Read More »

Related Articles

Focus: New Form of Carbon Stores Lots of Gas
Graphene

Focus: New Form of Carbon Stores Lots of Gas

Carbon honeycomb, a new carbon structure, could store large amounts of hydrogen gas, which may benefit fuel cell technology. Read More »

Synopsis: Trees Crumbling in the Wind
Materials Science

Synopsis: Trees Crumbling in the Wind

Lab experiments with wooden rods help explain why all trees—irrespective of size or species—break when battered by wind blowing at the same critical speed. Read More »

Synopsis: Growing Crystals in Macrosteps
Materials Science

Synopsis: Growing Crystals in Macrosteps

Simulations describe how crystals are able to grow past impurities by forming multilayer steps. Read More »

More Articles