In 1543, Copernicus boldly proposed the heliocentric model, asserting that the Earth revolved around the sun. Despite facing initial skepticism, his groundbreaking theory eventually gained widespread acceptance, albeit after a considerable period of time.
Similarly, esteemed materials scientist Takeshi Egami has dedicated his career to unraveling the intricate atomic structure of metallic glass and other liquids, often challenging the entrenched beliefs of the scientific community. His relentless pursuit of knowledge and willingness to engage with skeptics have been pivotal in garnering support for his latest discoveries.
The amorphous atomic structure of liquids and glasses presents a bewildering landscape, with atoms scattered in a seemingly chaotic manner akin to tapioca pearls in freshly shaken boba tea.
Egami conducts his research at the Department of Energy’s Oak Ridge National Laboratory and the University of Tennessee, Knoxville. Formerly, he led the UT-ORNL Joint Institute for Neutron Sciences from 2008 to 2015. Collaborating with colleagues in ORNL’s Materials Science and Technology Division, Egami employs neutron scattering and synchrotron X-ray techniques to gain increasingly detailed insights into the structure, dynamics, transitions, and deformations of noncrystalline materials.
Unlike crystalline solids, which exhibit a rigid lattice structure formed by bonded atoms, noncrystalline materials lack this orderly arrangement, offering a fascinating contrast that challenges traditional notions of solidity.
“There’s not much freedom for atoms to move around,” said Egami. “A crystalline structure is like an autocracy where each atom must behave like every other atom. A liquid is like a democracy where atoms may move about more.” Structural analysis is challenging since atoms are in constant disarray.
The traditional approach to atomic modeling involves a bottom-up method where each atom connects with its closest neighboring atoms. While this method is reliable for most solids, analyzing noncrystalline materials from the bottom up has always unsettled Egami due to their unstable, chaotic nature.
“The bottom-up approach is very self-centered, like the geocentric view of the universe where the Earth is at the center,” he said. Similar to Copernicus, Egami has devoted his career to uncovering the fundamental truths about these materials.
Following his undergraduate studies in applied physics at the University of Tokyo, a doctorate in materials science from the University of Pennsylvania, and postdoctoral studies at the University of Sussex and the Max Planck Institute, Egami spent 30 years teaching at the University of Pennsylvania. In 2003, he joined ORNL to pioneer advancements in the underdeveloped field of liquid physics.
“Water itself is a major mystery,” said Egami. “The classical physics of water is well understood, but there are many things about water we don’t understand. It’s such basic stuff, right? Life came out of that, and we don’t know why.”
Egami utilizes metallic glass to study noncrystalline materials. This unique material, with its disordered atomic structure, offers exceptional elasticity, strength, and magnetization capabilities. Despite its widespread use, its mechanical properties remain a mystery, limiting its full commercial potential.
Metallic glass may seem strong at first glance, but give a golf ball one too many whacks with a club made of it, and the club will shatter. This kind of weirdness challenges current theories about metallic glass. Egami’s groundbreaking research has begun to uncover the structural and functional behavior of noncrystalline materials that defies prevailing theory, with the potential for wide scientific impact.
In 2017, Egami and his group used synchrotron X-rays at the SPring-8 facility in Japan to reveal dynamic atomic correlation in water for the first time. These correlations measure how much the movement of one atom is influenced by the presence of others. “Now, we can see how atoms relate in space and time for the first time,” said Egami.
Egami’s journey to a new density wave theory began with his uneasiness with bottom-up atomic modeling. His new approach focuses on the medium-range order, which explores the correlation of a single atom and its surrounding atoms at a distance up to 10 times the atomic size.
In a 2022 paper, Egami and UTK’s Chae Woo Ryu unveiled a revolutionary discovery: a density wave state, previously mistaken for experimental noise, was confirmed to be real. By employing a cutting-edge experimental method of liquid levitation under vacuum, Egami’s team eliminated the noise and validated the existence of these elusive ripples. This pivotal finding not only validated the density wave theory but also sparked a new hypothesis regarding the interplay between bottom-up and top-down research methods.
Egami remarked, “Sometimes, conflict can lead to the creation of something entirely novel.” The clash between bottom-up and top-down observations prompted Egami and his colleagues to propose a groundbreaking concept of medium-range order, which holds the potential to unlock the secrets of viscosity and deformation in liquids and glasses. With these findings, Egami aspires to shatter the metallic glass ceiling, transcending the confines of the samples they were tested on. Moreover, scientists are leveraging density functional theory to calculate and predict the electron behaviors of intricate systems.
“Chemists use this all the time because it’s easier than running an experiment,” said Egami. However, the calculation is not ideal for materials in which electrons are strongly correlated, such as magnets or high-temperature superconductors. Using the same approach for electrons as he used for liquids, Egami has succeeded in seeing electron correlation. “Since we can see dynamic electron correlation, we no longer need to rely on density functional theory.”
The esteemed materials scientist is on a mission to share his groundbreaking findings with the world. Undeterred by initial resistance, he is taking his research on the road, embarking on a one-man talking tour to spread the word. “I know this will take some time to catch on,” he said, displaying unwavering determination.
His co-authored book, which initially faced great resistance, proposed a revolutionary method of analyzing disorganized crystals. After a decade of perseverance, his colleagues finally came around, and his analysis technique, detailed in “Underneath the Bragg Peaks,” is now the standard in the field.
Despite the challenges, the scientist remains optimistic about the acceptance of his proposed density wave theory and medium-range order of metallic glasses.
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