Diamonds aren’t forever

Kristin Persson, Gerbrand Ceder and Wenhao Sun at Lawrence Berkeley National Laboratory on Thursday, November 17, 2016 in Berkeley, Calif. 11/17/16

Related Posts

A new study from the Lawrence Berkeley National Laboratory deepened scientific understanding of nearly 30,000 materials by quantifying their thermodynamic scale of metastability, a breakthrough that paves the way for future innovations in technologies like batteries and solar power.

A material is metastable when it exists at a state other than its most stable, according to the study’s lead author, campus postdoctoral fellow Wenhao Sun. The thermodynamic scale expresses the difference in energy between the stable and metastable state of a material — information that helps scientists and engineers create the materials.

Sun offered chocolate as an example of a common material that’s often in a metastable state.

“If you chew stable chocolate, it doesn’t melt in your mouth,” Sun said. “It has the same makeup, but because it has a different structure (than metastable chocolate), it has different properties.”

Chocolate is manufactured in its metastable form because that state has a lower melting point. But over time, chocolate will get a “white, nasty exterior,” Sun said, as it reverts to its stable state.

Similarly, many pharmaceuticals are sold in their metastable form so that they’re easier to digest. And diamond is in fact a metastable form of carbon, meaning that over approximately 100,000 years it will revert to graphite, according to Sun.

“We measured that number, the thermodynamic metastability, for all known inorganic materials,” Sun said. “It’s an astounding statement. We did it for everything that is in our database, and we have a big database.”

The team used data from the Materials Project — a database of more than 60,000 substances, which Sun called the “Google of materials.” The Material Project’s director Kristin Persson and associate director Gerbrand Ceder were also heavily involved in the study.

According to William Tumas, the director of the Center for the Next Generation of Materials of the Design Energy Frontier Research Center, who was involved in the study, the large databases of the Materials Project are vital to best understand the data.

“(The study) creates understanding to think about how to make these materials and how to design and discover new ones,” Tumas said.

Sun said the team hopes its work will encourage further exploration of metastable materials.

“In the past people were looking for new materials within one space: stable materials,” Sun said. “Now we’ve proposed that this other huge space may also be exciting and worth pursuing.”

James Analytis, a campus physics professor unassociated with the study, said in an email that the search for new materials is crucial.

“New materials are the ‘uncharted waters’ of condensed matter physics,” Analytis said in the email. “Their properties have the potential to give us new methods to generate, transport and store energy, faster and better ways to communicate and from an academic standpoint, can change the way we think about the world.”

Contact Lillian Holmes at [email protected] and follow her on Twitter at @LillianQHolmes.