A Duke University-led group of scientists has engineered a new class of materials capable of producing tunable plasmonic properties while withstanding high temperatures.
“The standard metals used in plasmonics research, such as gold, silver, and copper, melt at relatively low temperatures and need protection from the elements,” said Arrigo Calzolari, a researcher at the Istituto Nanoscienze of Consiglio Nazionale delle Ricerche in Modena, Italy. “That means they can’t be used in rockets, satellites, or other aerospace applications. But these new materials we are developing open a completely new working arena because they can create plasmonic effects at incredibly high temperatures.”
The abilities come from a class of disordered ceramics discovered by Dr. Stefano Curtarolo, Professor of Mechanical Engineering and Materials Science at Duke, in 2018 called “high-entropy” carbides. Eschewing the reliance on the crystalline structures and bonds that keep traditional materials together, these carbides rely on a combination of many disorderly elements of various sizes to enhance stability.
The original group of high-entropy materials was made of carbon and five different metallic elements — technically a class of carbides. Since then, Curtarolo has secured a $7.5 million grant via the U.S. Department of Defense’s Multidisciplinary University Research Initiative (MURI) competition to develop a suite of AI-material tools capable of designing similar materials with tailored properties on demand.
Calzolari knew about the project as well as these materials — and also knew that tantalum carbide, a parent yet simpler system, is extremely durable and exhibits plasmonic abilities in the visible spectrum. However, the material can’t be tuned to different frequencies of light outside of its natural range, limiting its usefulness in real-world applications.
The two joined forces on a hunch that certain recipes for high-entropy carbides — especially those with tantalum — could demonstrate tunable plasmonic properties across a wide spectrum. Less than a half-year later, they were vindicated.
“Arrigo came to me to make sure these carbide mixtures would work and that they would have plasmonic properties,” Curtarolo said. “After running the recipe ideas through the disorder models and calculations we’ve been developing, we discovered that they do have plasmonic properties, and that we can tune them by tweaking the recipes.”
The research shows that 14 different high-entropy recipes demonstrate plasmonic properties across the near-infrared and visible spectrum of light, making them viable for optical and telecommunication applications.
“These materials bring together plasmonics, hardness, stability, and high temperatures into a single material,” Curtarolo said. “And they can be tailored to specific applications, which isn’t possible using standard materials because you can’t change properties defined by nature.”
Here is a Tech Briefs interview with Curtarolo, edited for clarity.
Tech Briefs: What inspired the research?
Stefano: Curiosity and progress inspired the research.
Tech Briefs: What were the biggest technical challenges?
Curtarolo: People. It is never about funding or equipment; it is always about a lack of skilled people.
Tech Briefs: Can you explain in simple terms how it works as well as how the carbides can revolutionize aerospace technology?
Curtarolo: It’s a combination of heat management, heat protection, hardness, and chemical resistance.
Tech Briefs: How far away are we from this practice becoming ubiquitous to the aerospace technology industry?
Curtarolo: Due to the cost of the materials, it will never become ubiquitous in the current used technologies, but it will push — big time — the boundaries of niche applications.
Tech Briefs: Do you have any advice for scientists aiming to bring their ideas to market?
Curtarolo: The market follows innovation; innovation follows progress. So the best advice for the scientists is the simplest possible one: a combination of education, passion, and hard work. The rest — success and funding — will follow naturally.
Tech Briefs: Is there anything else you’d like to add?
Curtarolo: Education, education, education!