Research studies investigate how minute features in nanomaterials, referred to as triple junctions, are essential for preserving the stability of these materials when exposed to high temperatures.
What strategies can we use to create materials that are both stronger and lighter? Can we design new materials that can withstand extreme environments, like those found in jet engines and spacecraft?
Fadi Abdeljawad, an associate professor of materials science and engineering at Lehigh University’s P.C. Rossin College of Engineering and Applied Science, suggests that the answer may lie in the minuscule regions, or boundaries, where atomic structures in crystals converge.
Teaming up with his colleagues from the U.S. Department of Energy’s Center for Integrated Nanotechnologies (CINT), Abdeljawad is revealing the significant role these microscopic boundaries play in the properties of nanomaterials.
“Nanocrystals are formed when atoms combine, and they are incredibly tiny, measuring about one-ten-thousandth the width of a human hair,” Abdeljawad explains. “You can think of these crystals coming together like the pieces of a puzzle or the tiles on a kitchen floor. Billions of these nanocrystals stack together to create most engineered materials.”
Research indicates that the areas where these crystals intersect are crucial in determining a material’s performance. Recently, the group’s findings were published in Nano Letters, a high-impact journal that highlights groundbreaking research in nanoscience and nanotechnology.
The paper, titled “Triple Junction Segregation Dominates the Stability of Nanocrystalline Alloys,” which was released on July 29, discusses how tiny features in nanomaterials, referred to as triple junctions, are vital for maintaining stability under high-temperature conditions.
Gold at the Corners
Nanocrystalline materials are characterized by an exceptionally fine structure composed of numerous small crystals. While this tiny crystal size can enhance material strength, achieving and sustaining the small, stable size over time can be challenging, as these crystals have a tendency to grow, which can compromise the material’s integrity.
The researchers in this investigation have found that the secret to preserving the stability of these materials at elevated temperatures resides in the triple junctions, which are the points where three nanocrystals converge. Envision the connection points of three puzzle pieces.
The team discovered that when certain atoms are included to form an alloy, they have a tendency to position themselves at these triple junctions. This phenomenon, referred to as “chemical segregation,” where atoms cluster at these junctions, aids in curbing grain growth and preventing the material from weakening over time.
This particular research showed that placing gold atoms selectively at the triple junctions in a platinum nanomaterial allowed it to maintain its stability under high-temperature conditions.
“By comprehending this mechanism,” states Abdeljawad, “researchers can engineer superior nanocrystalline alloys. They can select specific elements that will migrate to the triple junctions for material stabilization. This knowledge is especially crucial for applications where temperature resistance and durability are vital, such as in the aerospace and energy sectors.”
Harnessing Collaborative Efforts
Abdeljawad, a computational materials scientist at Lehigh, conducted large-scale computational analyses that predicted these findings. To support these models, the computational team collaborated with the Center for Integrated Nanotechnologies (CINT). CINT offers advanced resources and expertise for nanoscale studies, enabling innovations in materials science, nanofabrication, and nanophotonics to propel scientific and technological progress.
“This exemplifies exemplary collaborative science,” remarks Dr. Brad Boyce, a senior scientist at CINT and co-author of the study. “Our concepts for creating innovative materials by fine-tuning nanoscale features are evolving thanks to our ability to simulate the intricate arrangements of atoms constituting these materials.”
CINT is one of five Nanoscience User Facilities supported by the US Department of Energy Office of Science. It operates cooperatively with Sandia National Labs and Los Alamos National Lab, both located in New Mexico. The two facilities, one in Albuquerque and another in Los Alamos, provide unique capabilities and expert scientists to advance nanoscience research, offering these vital resources free of charge to user scientists who are selected based on a peer-reviewed two-page proposal.
