UCLA Breakthrough Maps Atoms in Amorphous Materials with Unprecedented Precision

Researchers at the California NanoSystems Institute at UCLA have unveiled a groundbreaking, step-by-step framework for precisely determining the three-dimensional positions and elemental identities of atoms within amorphous materials. Unlike crystals, amorphous solids like glass lack the repeating atomic patterns that have traditionally simplified atomic structure determination. The team meticulously analyzed simulated electron-microscope data to rigorously assess the accuracy of each stage of their innovative framework.

Leveraging advanced algorithms to analyze simulated imaging data of nanoparticles, the UCLA team achieved 100% accuracy in mapping the three-dimensional positions of silicon and oxygen atoms in amorphous silica, the fundamental component of glass. This remarkable feat was accomplished with a staggering precision of approximately seven trillionths of a meter under specific imaging conditions.

A Century of Atomic Structure Challenges

For over a century, the determination of three-dimensional atomic structures was almost exclusively confined to crystal structures. This was largely due to crystals' inherent repeating patterns, which allowed for averaging techniques to reveal their atomic arrangements. The formidable precision and accuracy needed to map individual atoms within a single, non-repeating structure – the defining characteristic of amorphous materials – remained an enduring challenge until recent technological advancements. The ability to image amorphous materials in 3D at the atomic level is poised to usher in a new era of profound impact across science and engineering disciplines.

Cutting-Edge Imaging Techniques Drive Breakthrough

The foundation of this study rests upon two sophisticated imaging techniques, both pioneered by corresponding author Jianwei "John" Miao, a distinguished professor of physics and astronomy at UCLA.

Atomic Electron Tomography (AET)

This method operates by capturing a series of images from multiple distinct angles as an electron beam traverses a sample. These numerous projections are then fed into advanced computational reconstruction algorithms to generate a precise three-dimensional map of the atoms within the material.

Ptychography

A powerful computational microscopy technique, Ptychography works by recording the intricate patterns of scattered electrons produced as a finely focused beam systematically scans across a sample. Subsequent algorithms are then employed to reconstruct a detailed image, bypassing the need for a traditional physical lens.

To ensure the robustness of their framework, the research team employed rigorously simulated AET and ptychographic data. These simulations were meticulously designed to faithfully replicate the complex conditions encountered in real experimental settings. Their sophisticated algorithms were specifically engineered to account for and mitigate potential sources of error, including common challenges like image noise, subtle focus variations, and the atomic vibrations induced by ambient temperatures. Crucially, electron scattering simulations, grounded in the principles of quantum mechanics, were integrated to accurately model these physical factors. Furthermore, the computational process intelligently incorporated known constraints, such as the specific types of atoms present and their typical inter-atomic distances, to iteratively refine and optimize the final 3D atomic map.

Far-Reaching Impact on Science and Technology

The field of computational microscopy, encompassing techniques like AET and Ptychography, is on a trajectory for continuous enhancement. Ongoing advancements in programming and hardware are expected to progressively elevate the capabilities of 3D atomic imaging. The ability to precisely unlock the 3D atomic structure of amorphous materials is anticipated to be a catalyst for significant technological innovation and to deepen our understanding of fundamental aspects of nature.

Consider amorphous glass, a ubiquitous material. A vast array of emerging technologies — from ultrathin electronics and advanced solar cells to novel rewritable memory, sophisticated medical devices, and cutting-edge quantum technologies — frequently rely on materials that, like glass, inherently lack long-range atomic order. This breakthrough could revolutionize their design and performance. Looking ahead, future applications hold the promise of extending to biological 3D imaging. This will become feasible once further advancements enable the precise identification of individual carbon and nitrogen atoms, elements critical for life and structurally akin to oxygen, which was successfully mapped in this landmark study.

Authorship and Support

The lead author of this seminal study is UCLA postdoctoral researcher Yuxuan Liao. Contributing co-authors include Haozhi Sha, Colum O'Leary, and Hanfeng Zhong from UCLA, alongside Yao Yang from Westlake University. The research received crucial support from STROBE, a National Science Foundation Science and Technology Center, and the U.S. Air Force Office of Scientific Research. The findings of this significant work were published in the esteemed scientific journal, Nature.