When it comes to metallurgy, it is known that smaller grains produce harder metals. But how exactly do you make these cereals?
A group of researchers at Brown University has found a method for breaking individual metal nanoclusters that leads to metals that are up to four times heavier than natural structures. This new method is quite different from conventional hardening techniques.
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“Hammering and other hardening methods are all top-down ways to change the structure of grain, and it’s very difficult to control the size of grain you get,” Ou Chen, an assistant professor of chemistry at Brown, said in a press release. corresponding author of the new research.
“What we’ve done is create nanoparticle building blocks that come together when you assemble them. Thus we can have uniform granule sizes that can be precisely adjusted for improved properties. ”
For this research, the team used nanoparticles of gold, silver, palladium and other metals and chemically removed organic molecules called ligands, which generally prevent the formation of metal-metal bonds between particles. The clusters were then able to merge together with just a little pressure.
The new metal coins made with this technique proved to have electrical conduction and light reflectance practically identical to standard metals, but their optical properties have been dramatically changed.
Because of what is known as the plasmonic effect, gold nanoparticles are actually black-purple, Chen said. “But when we apply pressure, we see that these purple groups suddenly turn into a bright golden color. This is one of the ways I knew I actually formed bulk gold. ”
Researchers are now looking to apply the technique to commercial products because the chemical treatment is relatively simple to perform. Chen is currently patenting the technique and sees great potential for it “both for the industry and the scientific research community.”