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Hierarchical densification and negative thermal expansion in Ce-based metallic glass under high pressure

TitleHierarchical densification and negative thermal expansion in Ce-based metallic glass under high pressure
Publication TypeJournal Article
Year of Publication2015
AuthorsLuo, Q, Garbarino, GT, Sun, BA, Fan, DW, Zhang, Y, Wang, Z, Sun, YJ, Jiao, J, Li, XD, Li, PS, Mattern, N, Eckert, J, Shen, J
JournalNature Communications
Volume6
Pagination5703
Date Published02
Type of ArticleArticle
ISBN Number2041-1723
Accession NumberWOS:000350034400001
Keywords1st-order transition, amorphous ice, elastic properties, free-volume, liquid phase-transition, Medium-range order, polyamorphism, temperature
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.

DOI10.1038/ncomms6703
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