Determining the Three-dimensional Atomic Structure of an Amorphous Solid

Determining the 3D atomic structure of a multi-component glass-forming nanoparticle with atomic electron tomography (AET). a) Representative experimental image, where some crystalline features are visible. Scale bar, 2 nm. b) Average 2D power spectrum of 55 experimental images, showing the amorphous halo. c & d) Two 2.4-A-thick slices of the 3D reconstruction in the x–y (c) and y–z (d) plane, where the majority of type-3 atoms (bright dots) are distributed in the second coordination shell. e) Experimental 3D atomic model of the glass-forming nanoparticle.
Determining the 3D atomic structure of a multi-component glass-forming nanoparticle with atomic electron tomography (AET). a) Representative experimental image, where some crystalline features are visible. Scale bar, 2 nm. b) Average 2D power spectrum of 55 experimental images, showing the amorphous halo. c & d) Two 2.4-A-thick slices of the 3D reconstruction in the x–y (c) and y–z (d) plane, where the majority of type-3 atoms (bright dots) are distributed in the second coordination shell. e) Experimental 3D atomic model of the glass-forming nanoparticle.

Amorphous solids such as glass, plastics and amorphous thin films are ubiquitous in our daily life and have broad applications ranging from telecommunications to electronics and solar cells. However, owing to the lack of long-range order, the three-dimensional (3D) atomic structure of amorphous solids has so far eluded direct experimental determination. Here an atomic electron tomography reconstruction method has been developed to experimentally determine the 3D atomic positions of an amorphous solid. Using a multi-component glass-forming alloy as proof of principle, the short- and medium-range order of the 3D atomic arrangement was quantitatively characterized. It was observed that, although the 3D atomic packing of the short-range order is geometrically disordered, some short-range-order structures connect with each other to form crystal-like superclusters and give rise to medium-range order. Four types of crystal-like medium-range order were identified. coexisting in the amorphous sample, showing translational but not orientational order. These observations provide direct experimental evidence to support the general framework of the efficient cluster packing model for metallic glasses. This work will pave the way for the determination of the 3D structure of a wide range of amorphous solids, which could transform our fundamental understanding of non-crystalline materials and related phenomena.

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Designing Materials to Revolutionize and Engineer our Future (DMREF)