title: Hierarchical densification and negative thermal expansion in Ce-based metallic glass under high pressure.
abstract: The polyamorphsim in amorphous materials is one of the most fascinating topics in condensed matter physics. In amorphous metals, the nature of polyamorphic transformation is poorly understood. Here we investigate the structural evolution of a Ce-based metallic glass (MG) with pressure at room temperature (RT) and near the glass transition temperature by synchrotron X-ray diffraction, uncovering novel behaviours. The MG shows hierarchical densification processes at both temperatures, arising from the hierarchy of interatomic interactions. In contrast with a continuous and smooth process for the low- to medium-density amorphous state transformation at RT, a relatively abrupt and discontinuous transformation around 5.5 GPa is observed at 390 K, suggesting a possible weak first-order nature. Furthermore, both positive and abnormal-negative thermal expansion behaviours on medium-range order are observed in different pressure windows, which could be related to the low-energy vibrational motions and relaxation of the weakly linked solute-centred clusters.
authors: School of Materials Science and Engineering, Tongji University, Shanghai 201804, P.R. China.
authors: Qiang
authors: Q
authors: Luo
authors: European Synchrotron Radiation Facility (ESRF), BP22, 6 rue Jules Horowitz, 38043 Grenoble, France.
authors: Gaston
authors: G
authors: Garbarino
authors: IFW Dresden, Institute for Complex Materials, Helmholtzstr. 20, D-01069 Dresden, Germany.
authors: Baoan
authors: B
authors: Sun
authors: 1] Key Laboratory of High-temperature and High-pressure Study of the Earth's Interior, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550002, China [2] Center for High Pressure Science and Technology Advanced Research (HPSTAR), Changchun 130012, China.
authors: Dawei
authors: D
authors: Fan
authors: Ames Laboratory-USDOE, Iowa State University, Ames, Iowa 50011, USA.
authors: Yue
authors: Y
authors: Zhang
authors: IFW Dresden, Institute for Complex Materials, Helmholtzstr. 20, D-01069 Dresden, Germany.
authors: Zhi
authors: Z
authors: Wang
authors: School of Materials Science and Engineering, Tongji University, Shanghai 201804, P.R. China.
authors: Yajuan
authors: Y
authors: Sun
authors: School of Materials Science and Engineering, Tongji University, Shanghai 201804, P.R. China.
authors: Jin
authors: J
authors: Jiao
authors: Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, China.
authors: Xiaodong
authors: X
authors: Li
authors: Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, China.
authors: Pengshan
authors: P
authors: Li
authors: IFW Dresden, Institute for Complex Materials, Helmholtzstr. 20, D-01069 Dresden, Germany.
authors: Norbert
authors: N
authors: Mattern
authors: 1] IFW Dresden, Institute for Complex Materials, Helmholtzstr. 20, D-01069 Dresden, Germany [2] TU Dresden, Institute of Materials Science, D-01062 Dresden, Germany.
authors: Jürgen
authors: J
authors: Eckert
authors: School of Materials Science and Engineering, Tongji University, Shanghai 201804, P.R. China.
authors: Jun
authors: J
authors: Shen