Direct observation of atomic-level fractal structure in a metallic glass membrane

Hongyu Jiang; Jiyu Xu; Qinghua Zhang; Qian Yu; Laiquan Shen; Ming Liu; Yitao Sun; Chengrong Cao; Dong Su; Haiyang Bai; Sheng Meng; Baoan Sun; Lin Gu; Weihua Wang

doi:10.1016/j.scib.2021.02.020

Direct observation of atomic-level fractal structure in a metallic glass membrane

Sci Bull (Beijing). 2021 Jul 15;66(13):1312-1318. doi: 10.1016/j.scib.2021.02.020. Epub 2021 Feb 9.

Authors

Hongyu Jiang¹, Jiyu Xu¹, Qinghua Zhang², Qian Yu³, Laiquan Shen⁴, Ming Liu⁵, Yitao Sun¹, Chengrong Cao⁶, Dong Su¹, Haiyang Bai⁷, Sheng Meng⁷, Baoan Sun⁸, Lin Gu⁹, Weihua Wang⁷

Affiliations

¹ Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China.
² Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China; Songshan Lake Materials Laboratory, Dongguan 523808, China; School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100049, China. Electronic address: zqh@iphy.ac.cn.
³ Department of Materials Science & Engineering, Center of Electron Microscopy and State Key Laboratory of Silicon Materials, Zhejiang University, Hangzhou 310027, China.
⁴ Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China; Songshan Lake Materials Laboratory, Dongguan 523808, China.
⁵ Qian Xuesen Laboratory of Space Technology, Beijing 100094, China.
⁶ Department of Materials Science and Engineering, University of Wisconsin-Madison, Madison, Wisconsin 53706, USA.
⁷ Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China; Songshan Lake Materials Laboratory, Dongguan 523808, China; School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100049, China.
⁸ Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China; Songshan Lake Materials Laboratory, Dongguan 523808, China; School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100049, China. Electronic address: sunba@iphy.ac.cn.
⁹ Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China; Songshan Lake Materials Laboratory, Dongguan 523808, China; School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100049, China. Electronic address: l.gu@iphy.ac.cn.

PMID: 36654153
DOI: 10.1016/j.scib.2021.02.020

Abstract

Determination and conceptualization of atomic structures of metallic glasses or amorphous alloys remain a grand challenge. Structural models proposed for bulk metallic glasses are still controversial owing to experimental difficulties in directly imaging the atom positions in three-dimensional structures. With the advanced atomic-resolution imaging, here we directly observed the atomic arrangements in atomically thin metallic glassy membranes obtained by vapor deposition. The atomic packing in the amorphous membrane is shown to have a fractal characteristic, with the fractal dimension depending on the atomic density. Locally, the atomic configuration for the metallic glass membrane is composed of many types of polygons with the bonding angles concentrated on 45°-55°. The fractal atomic structure is consistent with the analysis by the percolation theory, and may account for the enhanced relaxation dynamics and the easiness of glass transition as reported for the thin metallic glassy films or glassy surface.

Keywords: Atomic-resolution imaging; Fractal packing; Metallic glass; Percolation theory.