- Yuan, Yakun;
- Kim, Dennis S;
- Zhou, Jihan;
- Chang, Dillan J;
- Zhu, Fan;
- Nagaoka, Yasutaka;
- Yang, Yao;
- Pham, Minh;
- Osher, Stanley J;
- Chen, Ou;
- Ercius, Peter;
- Schmid, Andreas K;
- Miao, Jianwei
Liquids and solids are two fundamental states of matter. However, due to the
lack of direct experimental determination, our understanding of the 3D atomic
structure of liquids and amorphous solids remained speculative. Here we advance
atomic electron tomography to determine for the first time the 3D atomic
positions in monatomic amorphous materials, including a Ta thin film and two Pd
nanoparticles. We observe that pentagonal bipyramids are the most abundant
atomic motifs in these amorphous materials. Instead of forming icosahedra, the
majority of pentagonal bipyramids arrange into networks that extend to
medium-range scale. Molecular dynamic simulations further reveal that
pentagonal bipyramid networks are prevalent in monatomic amorphous liquids,
which rapidly grow in size and form icosahedra during the quench from the
liquid state to glass state. The experimental method and results are expected
to advance the study of the amorphous-crystalline phase transition and glass
transition at the single-atom level.