Determining the three-dimensional atomic structure of a metallic glass

Abstract

Amorphous solids such as glass are ubiquitous in our daily life and have\nfound broad applications ranging from window glass and solar cells to\ntelecommunications and transformer cores. However, due to the lack of\nlong-range order, the three-dimensional (3D) atomic structure of amorphous\nsolids have thus far defied any direct experimental determination without model\nfitting. Here, using a multi-component metallic glass as a proof-of-principle,\nwe advance atomic electron tomography to determine the 3D atomic positions in\nan amorphous solid for the first time. We quantitatively characterize the\nshort-range order (SRO) and medium-range order (MRO) of the 3D atomic\narrangement. We find that although the 3D atomic packing of the SRO is\ngeometrically disordered, some SRO connect with each other to form crystal-like\nnetworks and give rise to MRO. We identify four crystal-like MRO networks -\nface-centred cubic, hexagonal close-packed, body-centered cubic and simple\ncubic - coexisting in the sample, which show translational but no orientational\norder. These observations confirm that the 3D atomic structure in some parts of\nthe sample is consistent with the efficient cluster packing model. Looking\nforward, we anticipate this experiment will open the door to determining the 3D\natomic coordinates of various amorphous solids, whose impact on non-crystalline\nsolids may be comparable to the first 3D crystal structure solved by x-ray\ncrystallography over a century ago.\n