If you drop an aluminum spoon in a sink full of water, the spoon will sink to the bottom. That's

because aluminum, in its conventional form, is denser than water says Utah State University

chemist Alexander Boldyrev.

But if you restructure the common household metal at the molecular level, as Boldyrev and co

lleagues did using computational modeling, you could produce an ultra-light crystalline form of

aluminum that's lighter than water. Boldyrev, along with scientists Iliya Getmanskii, Vitaliy Koval

, Rusian Minyaev and Vladimir Minkin of Southern Federal University in Rostov-on Don, Russi

a, published findings in the Sept. 18, 2017, online edition of The Journal of Physical Chemistry

C.

The team's research is supported by the National Science Foundation and the Russian Ministr

y of Science and Education.

"My colleagues' approach to this challenge was very innovative," says Boldyrev, professor in U

SU's Department of Chemistry and Biochemistry. "They started with a known crystal lattice, in t

his case, a diamond, and substituted every carbon atom with an aluminum tetrahedron.

The team's calculations confirmed such a structure is a new, metastable, lightweight form of cr

ystal aluminum. And to their amazement, it has a density of only 0.61 gram per cubic centimet

er, in contrast to convention aluminum's density of 2.7 grams per cubic centimeter.

"That means the new crystallized form will float on water, which has a density of one gram per

cubic centimeter," Boldyrev says.

Such a property opens a whole new realm of possible applications for the non-magnetic, corro

sive-resistant, abundant, relatively inexpensive and easy-to-produce metal.

"Spaceflight, medicine, wiring and more lightweight, more fuel-efficient automotive parts are so

me applications that come to mind," Boldyrev says. "Of course, it's very early to speculate abo

ut how this material could be used. There are many unknowns. For one thing, we don't know a

nything about its strength."

Still, he says, the breakthrough discovery marks a novel way of approaching material design.

"An amazing aspect of this research is the approach: using a known structure to design a new

material," Boldyrev says. "This approach paves the way for future discoveries."