A novel computational approach reveals numerous fresh ceramic materials showcasing a diverse array of properties, potentially disruptive for various industries—imagine electronics capable of functioning even within lava.
Ceramics" />
One potential use for heat-impervious electronics is in the aviation industry. Image Credit: PRATT School of Engineering
Under the direction of Duke University materials scientists, a research team has created a technique for quickly identifying a new class of materials with electrical and heat tolerances so robust that they could allow devices to operate at temperatures above several thousand degrees Fahrenheit, similar to lava.
These materials, which are more durable than steel and stable in corrosive environments, have the potential to serve as the foundation for novel applications such as coatings that are resistant to wear and corrosion, thermoelectric, batteries, catalysts, and radiation.
The recipes for these materials, which are ceramics based on carbonitrides or borides of transition metals, were found using a novel computational technique known as Disordered Enthalpy-Entropy Descriptor (DEED).
The program anticipated that 900 novel high-performance material formulations would be synthesizable in its initial demonstration; 17 of these formulations were successfully tested and manufactured in labs.
Collaborations from Penn State University, Missouri University of Science and Technology, North Carolina State University, and State University of New York at Buffalo are included in the results, which are published online in the journal Nature on January 3rd, 2024.
The capability of rapidly discovering synthesizable compositions will allow researchers to focus on optimizing their industry-disrupting properties.
Stefano Curtarolo, Edmund T. Pratt Jr. School Distinguished Professor, Mechanical Engineering and Materials Science, Duke University
The Duke Automatic-FLOW for Materials Database (AFLOW), which is connected to other online resources for materials optimization, is a vast repository of material characteristics data that the Curtarolo group manages. This abundance of data makes it possible for computers to predict features of unknown mixes with high accuracy without requiring the complicated atomic dynamics to be replicated or created in a lab.
The Curtarolo group has been working on developing predictive capabilities for "high-entropy" materials for a few years now. These materials do not rely just on the orderly atomic structure of conventional materials; instead, they gain improved stability from a chaotic combination of atoms. They found high-entropy carbides in 2018, which was a more straightforward case study.
Curtarolo said, “The high-entropy carbides all had a relatively uniform amount of enthalpy so that we could ignore part of the equation, but to predict new ceramic recipes with other transition metals, we had to address the enthalpy.”
Consider a 10-year-old who is attempting to build a doghouse out of an enormous mound of Legos to gain a better understanding of the principles of entropy and enthalpy in this application. There would be a wide range of potential design outputs even with a restricted selection of construction blocks.
To put it simply, entropy is a measure of the number of alternative designs that have equivalent strength, while enthalpy is a measure of how sturdy each design is. The first encourages structured arrangements similar to those seen in instruction manuals.
The latter depicts the inevitable mayhem that results from the child devoting more time and attention to the increasingly perplexing construction project. Both indicate how much heat and energy are ultimately absorbed into the finished product.
Curtarolo explained, “To rapidly quantify both enthalpy and entropy, we had to calculate the energy contained within the hundreds of thousands of various combinations of ingredients that we could potentially create instead of the ceramics we’re looking for; it was a mammoth undertaking.”
In addition to forecasting novel formulas for stable disordered ceramics, DEED guides more research into these materials to uncover their underlying characteristics. To choose the best ceramics for different uses, scientists will need to hone these computations and put them through actual laboratory testing.
DEED is designed specifically for a manufacturing process known as hot-pressed sintering. To do this, powdered forms of the component chemicals are heated to temperatures as high as 4000 ºF under vacuum pressure for periods of time that may extend to several hours. It takes more than eight hours to complete the procedure, including all of the preparation, reaction, and cooling phases.
The final step in synthesis, called spark plasma sintering, is an emerging method in materials science that is common in research labs.
William Fahrenholtz, Curator's Distinguished Professor, Ceramic Engineering, Missouri University of Science and Technology
The completed ceramics seem dark grey or black and have a metallic sheen. They feel and have a similar density to metal alloys like stainless steel, but they look much darker. Furthermore, they are strong and brittle, like traditional ceramics, despite their metallic appearance.
The team anticipates that in the future, further researchers will use DEED to create and evaluate novel ceramic materials for a range of uses. They think it will be a question of time before some of them are put into commercial production because of their astounding diversity of potential qualities and uses.
Spark plasma sintering or field-assisted sintering technology (FAST) is not a common technique in the industry yet; however, current ceramic manufacturers could pivot to making these materials by making small adjustments to existing processes and facilities.
Doug Wolfe, Professor and Associate Vice President, Research, Materials Science and Engineering, Pennsylvania State University
This research was funded by a five-year, $7.5 million grant through the US Department of Defense’s Multidisciplinary University Research Initiative (MURI) competition led by Curtarolo (N00014-21-1-2515, N00014-23-1-2615) and the Department of Defense High-Performance Computing Modernization Program (HPC-Frontier).
Journal Reference
Divilov, S., et,al., (2024). Disordered enthalpy–entropy descriptor for high-entropy ceramics discovery. Nature. doi.org/10.1038/s41586-023-06786-y.