Vladan Stevanovic wins NSF CAREER Award for work to discover new metastable materials

Vladan Stevanovic, assistant professor of metallurgical and materials engineering at Colorado School of Mines, has received a National Science Foundation CAREER Award for work that could accelerate the discovery of new metastable materials.

Invaluable to our daily lives, metastable materials remain a bit of a mystery to scientists. These forms of matter are long-lived in environments and conditions at which, according to thermodynamics, they should spontaneously transform into more stable forms, like diamonds into graphite or glass into quartz.

Stevanovic will receive $521,376 over five years for his project, “Toward Rational Discovery and Design of Metastable Materials,” which aims to enable rational and reliable discovery and design of new metastable materials.

Here, Stevanovic answers a few questions about his research and how, of all materials, chocolate factors in.

Q: What is your latest research focused on?

A: Metastable materials are those that eventually would transform into some other form. The key word is “eventually.” For example, diamond is a metastable form of carbon – eventually it would convert into graphite. But wedding rings are fine. They’re not going to transform into graphite over the time interval of a marriage. You have short-lived metastable states and long-lived metastable states, and right now, we’re really bad at rationally discovering long-lived and useful metastable states. The question we’re asking is, how can we rationally predict and discover metastable states that live for a long time and have useful properties?

Why does this matter? If you are looking for the hardest material on Earth, and you don’t consider metastable states, you just missed diamond, which is the hardest material that we know. That’s the reason why. Glass is another very useful material, and another metastable system. It is an amorphous version of silicon dioxide. The stable form is quartz, the crystalline form.

Solid chocolate, the version of chocolate that we like to consume as the chocolate bars—the most expensive one when you go to the store is called polymorph 5. It is the specific metastable form of cocoa butter, the key ingredient in chocolate. If you let a chocolate bar melt and then solidify on its own, you will never get that same shiny, snappy version of chocolate. You will get a dull brownish thing that leaves marks on your fingers—the taste is OK but the texture isn’t really good.

I’m a theoretical material scientist – my core thing is to try to develop methodologies to discover new and more useful materials. New theory needs to be developed that is sufficiently predictive about experimental synthesis of these types of things.

Q: What do you find most exciting about your research?

A: The opportunities that metastable materials offer. You could enable some property in a metastable state that doesn’t exist in the most stable form. Graphite is not as hard as diamond – it’s actually very soft. If you scratch it against a piece of paper, it leaves traces. That’s how we write. Diamonds don’t do that. But you have to pay the price – making metastable states is a hard endeavor.

Q: What is the potential impact of this work?

A: You could find functionalities that are mind-blowing and game-changing in chemistries that you would not expect. You could find super-hard materials, for example. I work on semiconductors – you could find the coexistence of electric conductivity and optical transparency, which isn’t common. That coexistence could enable having a fully transparent and conductive material – imagine something that looked like glass but with the functionality of a TV screen, like in that Tom Cruise movie “Minority Report.” If you could find transparent semiconductors like that, you could have Google Maps displayed on your windshield and the arrows pointing to where you need to turn. You could enable better materials for renewable energy applications. You could make things more efficient.

You never know what you’re going to discover until you discover it. It’s an endeavor. It's an investigation. It’s uncharted territory with a lot of opportunities.

Q: How does this research agenda inform your teaching?

A: By developing a new theory and new metastable materials, we could transform how we teach about metastability and metastable states. The way we teach right now, it’s not very quantitative. It’s more of a fairy tale. It’s a lot of words and not a lot of equations. Through this project, we will have a more quantitative approach to metastable states. We’ll possibly have an addendum to the present theory that enables more quantitative predictions, which we will teach students. We’re also promising some online tools where you could investigate how properties change if you change the crystal structure of materials. We’ll create those type of tools so you can gauge your expectations or create your expectations.