Magnesium magnificent for plasmonic applications

Rice University researchers have synthesized and isolated plasmonic magnesium nanoparticles that show all the promise of their gold, silver and aluminum cousins with none of the drawbacks.

The Rice lab of materials scientist Emilie Ringe produced the particles to test their ability to emit plasmons, the ghostly electron bands that, when triggered by energy from outside, ripple across the surface of certain metals.
The research appears in the American Chemical Society journal Nano Letters.

Plasmonic materials are valuable because they can concentrate light and squeeze its power in nanoscale volumes, a useful property for chemical and biological sensors. They can also be used as photocatalysts and for medical applications in which they can, for instance, target cancer cells and be triggered to emit heat to destroy them.

But gold and silver are expensive. "They're just not affordable if you're trying to do cheap things on a very large scale, like industrial catalysis," said Ringe, an assistant professor of materials science and nanoengineering and of chemistry at Rice.

"We've been really excited aboutaluminum, because it's one of the only Earth-abundant plasmonic materials, but it has a critical flaw," she said. "Its intrinsic properties mean it is a good plasmonic in the ultraviolet range, but not as good in the visible and poor in the infrared. That's not so great it you want to do photocatalysis with the sun."

Those limitations set the stage for the Ringe lab's investigation of also-abundant magnesium. "It can resonate across the infrared, visible and ultraviolet ranges," she said. "People have been talking about it, but no one's really been able to make and look at the optical properties of single crystals of magnesium."