An international research group led by Duke University, including contribution from the Istituto Nanoscienze of the National Research Council of Italy in Modena (Cnr-Nano) and other U.S. universities, has developed a method to rapidly identify a new class of materials with exceptional thermal and mechanical tolerances. These materials, known as high-entropy ceramics, could form the basis for batteries, catalysts, and electronic devices resistant to temperatures of thousands of degrees or intense radiation. The research results are published in the journal Nature.

Extremely stable and performing in extreme environments, high-entropy ceramics have enormous potential applications, but their discovery is limited by lengthy and costly experimental processes. Now, hundreds of these materials can be discovered using a computational method called DEED (Disordered Enthalpy-Entropy Descriptor), capable of identifying high-entropy ceramics and predicting whether they can be experimentally synthesized. In its first demonstration, the program predicted the “synthetizability” of 900 new formulations of high-performance materials, ceramics made using transition metals, carbonitrides and borides, 17 of which were then produced and tested in the laboratory.

The algorithm was developed by a team led by Stefano Curtarolo of Duke University, in collaboration with Arrigo Calzolari of Cnr-Nano and colleagues from Penn State University, Missouri University of Science and Technology, North Carolina State University, and State University of New York at Buffalo

“High-entropy ceramics are alloys composed of a disordered mixture of many chemical elements, with hundreds of thousands of possible combinations influencing the synthesizability and properties of the material. The complexity and vastness of these possible combinations make it practically impossible to experimentally explore all potential recipes,” explains Arrigo Calzolari from Cnr-Nano. “Our computational approach, combining thermodynamics, statistical mechanics, and quantum simulations, allows us to find ‘feasible’ combinations, significantly accelerates the discovery of synthesizable ceramics for use in extreme environments. Such materials have exceptional structural, thermal, chemical, and optical properties are required at very high temperatures, thus are of great interest as they pave the way for the development of advanced electronic and optical devices for applications in satellite telecommunications, high-performance aviation, and energy management, including application in nuclear reactors”.

The Solution

The Disordered Enthalpy-Entropy Descriptor (DEED) quantifies the synthesizability of theoretical high-entropy carbides, carbonitrides, and borides using a specific production process – called hot-pressed sintering.

“One innovative aspect of the DEED descriptor is that the method captures both the ordering tendency—a penalizing contribution given by enthalpy—and the tendency for disorder—a stabilizing contribution given by entropy. This allows the correct classification of the synthesizability of multicomponent ceramics, regardless of their chemical and structural composition”, explain Calzolari. “Another advantage of DEED is that many ceramics have similar precursors. Consequently, a multitude of calculations can be efficiently reused by archiving them in a well-organized repository, like the AFLOW (aflow.org) database maintained by our team. This will make the analysis of new unexplored mixtures progressively more straightforward over time”.

Arrigo Calzolari collaborated with Professor Curtarolo’s group in the methodological development and realization of the computational solutions necessary for the implementation of numerical algorithms through the aflow++ software (automatic-flow framework for materials discovery).

DEED will be extended with other theoretical frameworks and experimental data. For example, DEED will be used in the search for multifunctional ceramic materials with adjustable light diffusion and absorption properties, capable of functioning in extreme environmental conditions. This combination of properties is useful for optical and telecommunication applications at high temperatures.