New Nanometal Changes from Hard to Soft at the Flip of a Switch

Materials scientists are constantly trying to tweak their products to be a little stronger, a little less brittle, a little more malleable–it’s the engineer’s job to imbue any material with the properties it needs to do its job. That often means striking a compromise between conflicting properties, but perhaps not for much longer. Researchers at the Technical University of Hamburg and the Helmholtz Center Geesthacht have engineered a new nanomaterial that changes from hard to soft with the flip of a switch.

The material is essentially an electrically tunable metal that can be hard and brittle or soft and malleable depending on the charge passing through it. To create the material, researchers placed precious metals like gold and platinum in an acidic bath, where corrosion cuts tiny porous channels or ducts through the metal. Those interior channels are then filled with a conductive liquid partner, like a diluted acid or saline solution.

Ions dissolved in the liquid can then influence the surface atoms of the metallic part of this metal-liquid combo. Depending on the charge applied to the liquid constituent, electrons are either added to or withdrawn from the metallic surface atoms, strengthening the material by double or making it more malleable and weaker (but more tolerant to damage) at will.

That’s a enviable quality for a metal to have. It opens the door to a variety of applications, including self-healing materials that can respond to stress in certain areas by becoming softer or harder as the situation commands.