The complex structure of liquid Cu(6)Sn(5) alloy
Jingyu Qin1, Hui Liu, Tingkun Gu
1The Key Laboratory of Liquid Structure and Heredity of Materials, Ministry of Education, Shandong University, Southern Campus, Jinan 250061, People's Republic of China.
Summary
This study reveals that liquid copper-tin (Cu(6)Sn(5)) alloys exhibit both hetero-coordination between Cu and Sn atoms and self-coordination among Sn atoms. These findings suggest complex structural ordering in this technologically relevant alloy.
Area of Science:
- Materials Science
- Computational Chemistry
- Condensed Matter Physics
Background:
- Understanding the atomic structure of liquid alloys is crucial for predicting their properties.
- Copper-tin (Cu-Sn) alloys are vital in soldering applications, but their liquid-state structure remains complex.
- Previous studies have indicated challenges in characterizing the short-range order in liquid Cu-Sn alloys.
Purpose of the Study:
- To investigate the local atomic structure and bonding characteristics of liquid Cu(6)Sn(5) alloy.
- To identify hetero-coordination tendencies and the nature of local environments for Cu and Sn atoms.
- To explore the existence of specific structural motifs within the liquid alloy.
Main Methods:
- Ab initio molecular dynamics (AIMD) simulations were employed to model liquid Cu(6)Sn(5).
- Bathia-Thornton partial correlation functions and a chemical short-range parameter were used to analyze hetero-coordination.
- Voronoi analysis was applied to characterize the local structural environment of Sn atoms.
Main Results:
- A clear tendency for hetero-coordination between Cu and Sn atoms was observed.
- The local structural environment of Sn atoms in l-Cu(6)Sn(5) resembles that of pure liquid Sn.
- A novel subpeak in the pair distribution function suggests the presence of topologically disordered β-Sn-type structural units.
Conclusions:
- Liquid Cu(6)Sn(5) alloy exhibits coexisting chemical short-range order (CSRO) between unlike atoms and self-coordination among Sn atoms.
- The findings indicate a complex interplay of bonding and structural arrangements at the atomic level.
- The presence of β-Sn-type units offers new insights into the structural disorder of liquid Cu-Sn alloys.
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